...bridged to the fediverse

Personal web site

...bridged to the Atmosphere (Bluesky)

Fediverse account

...bridged to the fediverse

Atmosphere (Bluesky) account

Bridgy Fed is a decentralized social network bridge. It connects the fediverse, the web, and the Atmosphere (Bluesky). If you're on one of these networks, you can use Bridgy Fed to follow people on other networks, see their posts, and reply and like and repost them. Likewise, they'll be able to see you and your posts too.

Click here to get started, or read on for more information and setup details.

About

• Which networks are supported?
• Who can see me and my stuff?
• What about other bridges?
• What's the difference between this and Bridgy classic, ie non-Fed?
• How does this handle behavior differences between networks?
• How does this handle formatting differences between networks?
• What about moderation? How do blocks, mutes, etc work?
• I got suspended or moderated or labeled as spam, NSFW, etc, but I'm not! What do I do?
• How do I disable the bridge?
• Why is Bridgy Fed chatting or DMing with me?
• Is account migration supported?
• Can I log into my bridged account and use it like a normal account?
• Can I use this to bridge two existing accounts that I already have?



Using

• How do I get started?
• Which accounts do I need?
• How do I update my profile?
• I tried it, and it didn't work!
• Can I see my account's status and recent activity?
• How does my bridged account's follower count work?
• How do I @-mention a bridged user?
• How do I delete a post?
• What happens when someone replies or interacts with me?
• How do I block someone in another network who's not bridged into mine?
• How do I subscribe to a blocklist?
• The *.brid.gy domain in my bridged account is ugly. Can I use my own domain instead?
• What commands can I DM the bot account?
• I want to follow someone, but they're not bridged!



From the fediverse

• How do I get started?
• How do I find a bridged Atmosphere (Bluesky) account?
• I can't find @bsky.brid.gy@bsky.brid.gy on the fediverse!
• How do I find a bridged web site?
• Which stuff of mine from the fediverse will get bridged?
• I'm a fediverse instance admin. What do I need to know?



To the fediverse

• How do I verify my profile links (ie get green checks) in Mastodon?
• Can I use my own domain as my fediverse handle?
• Will I show up in fediverse search engines and indexes?
• I disabled my bridged profile, or deleted a post, but it's still visible in the fediverse!
• Mastodon is showing bridged posts in the wrong order!
• Could other networks' instances get their own brid.gy subdomains, so that fediverse admins can federate with or block them individually?



From the Atmosphere (Bluesky)

• How do I get started?
• How do I find a bridged fediverse account?
• How do I find a bridged web site?
• Can I use Bluesky's reply controls?
• Is Bridgy Fed subject to Bluesky PBC's moderation? If Bluesky bans someone, and they move to a different PDS, can they still use Bridgy Fed?



To the Atmosphere (Bluesky)

• Which stuff of mine can get bridged into the Atmosphere?
• Which stuff can't get bridged into the Atmosphere?
• What happens when I report a bridged Atmosphere user?
• I edited a post, but it didn't get edited on the Atmosphere!
• Can I use my own domain as my Atmosphere handle?
• Can I verify my web site or domain with standard.site?
• Can I link my bridged web pages or articles to their standard.site documents?
• How can I see the full text or original URL for a bridged post?
• Why can't I see a video?
• My images or videos are blank in the Atmosphere!
• My images are broken or corrupted in the Atmosphere!



From the web

• How do I get started?
• Where does my profile info come from?
• How does Bridgy Fed find my posts?
• How does it decide which parts of my posts to include?
• What's up with the visible fed.brid.gy links in my fediverse posts?
• How do I reply to a post?
• How do I like or repost a fediverse or Atmosphere (Bluesky) post?
• How do I follow someone?
• How do I unfollow someone?
• How do I include an image in a post?
• How do I include a video in a post?
• How do I use hashtags?
• How do I @-mention someone?
• How do I edit an existing post?
• How do I delete a post?
• Can I publish just one part of a page?
• How do replies, likes, and other interactions show up on my site?
• How do I read my timeline/feed?
• Are there notifications?
• How can people find and follow me?
• How can I see what my posts look like?
• Can I make my posts show up when people search for their URLs?
• Can I verify my web site and use my domain as my handle on other networks?



Developers and admins

• Does Bridgy Fed have an API? Can I integrate my client or service or other tool with it?
• How can I tell if an account is bridged from another network?
• How can I tell if an account is bridged to another network?
• How can I tell if a post was bridged from another network?
• How can I tell if a post was bridged to another network?
• Can I get additional metadata about a bridged account or post?
• As a server admin, can I automatically enable the bridge for new users?
• As a server admin, can I give my new users custom Atmosphere (Bluesky) domain handles automatically?
• Can I give my users custom fediverse addresses automatically?
• As a client developer, can I show my user notifications, including from unbridged users?



Background

• Who are you? Why did you make this?
• How much does it cost? Can I donate or support you?
• What do you do with my data?
• How long has this been around?
• What are the terms of service?
• What is your content moderation policy?
• I found a bug! I have a feature request!
• I found a security vulnerability!
• What's your succession plan if you can't run Bridgy Fed any more?



Development

• What are Bridgy Fed's product and engineering values?
• How do the different protocols compare?
• How are the different protocols translated?
• How are activities routed?

About

• Which networks are supported?

• Bridgy Fed currently supports the web, fediverse, and the Atmosphere (Bluesky). We're considering adding more networks, including Farcaster and Nostr.

  All bridging is fully bidirectional. If you're on a supported network, you can use Bridgy Fed to follow and interact with bridged users on any other supported network.

• Who can see me and my stuff?

• If you haven't enabled the bridge for your account, no one. Once you enable it, Bridgy Fed only bridges fully public profiles and posts and interactions, not unlisted, quiet public, followers-only, or otherwise private posts or DMs. In other words, bridging your account doesn't expose your profile or posts to anyone new who couldn't already see them before.

• What about other bridges?

• Bridgy Fed is just one of many different bridges: pinhole, Fedisky, RSS Parrot, and mostr.pub, among others. They're great! They rarely reach the level of fully bidirectional federation that Bridgy Fed aims at, but they contribute to a diversity of approaches that we think is still valuable.

  These bridges don't interoperate right now, but we hope they will eventually. For example, where multiple bridges overlap, networks can end up with duplicate bridged accounts, which is obviously not ideal. FEP-fffd is one promising approach to this that we're following closely. We're open to other ideas!

• What's the difference between this and Bridgy classic, ie non-Fed?

• Bridgy Fed and Bridgy classic are separate services. They both connect web sites and social networks and translate posts and interactions back and forth, but they each do it very differently.

  Bridgy Fed - this service - bridges accounts on decentralized social networks like the fediverse, the Atmosphere (Bluesky), and the IndieWeb directly across those networks.

  Bridgy classic, on the other hand, connects IndieWeb web sites to existing accounts on social networks, both centralized and decentralized, and provides backfeed and POSSE (aka cross-posting) as a service.

  As an example, here's a visualization of how they each connect web sites to the fediverse:

  
  

  Bridgy cross-posts to a Mastodon account: @you@mastodon.server

        
      /
  🌐 —  — 
      \
        
  

  You already have a Mastodon account. You want to copy posts from your web site to Mastodon and send responses back to your site.

  Bridgy Fed connects directly to the fediverse: @yoursite.com

     
  \ /
   — 🌐 — 
  / \
     
  

  Your web site will be its own fediverse account. Its posts will show up in the fediverse automatically. People there can follow it directly.

  Apologies for the confusingly similar names!

• How does this handle behavior differences between networks?

• When networks work differently, we try to preserve each network's behavior as much as possible. For example, following on the web is permissionless: you can follow any web site in a feed reader. However, in the fediverse, following may require approval, ie users can choose to approve or reject each follower individually.

  Bridgy Fed cooperates with this. When a web user follows a fediverse user, Bridgy Fed only adds them and starts delivering posts once the fediverse user approves the follow.

• How does this handle formatting differences between networks?

• We work hard to preserve profile and post formatting as much as possible. For networks with rich formatting like the web, we convert that formatting to text-based formatting as much as possible when delivering to text-based networks.

  Unfortunately, this kind of conversion is never perfect. Some types of posts, eg events and polls, are difficult to represent in networks that don't support them. As a fallback, Bridgy Fed includes a link to the original post on its own network that users elsewhere can follow to see it as it was originally intended.

• What about moderation? How do blocks, mutes, etc work?

• In general, native moderation tools within each network work with bridged users just like with native users. Atmosphere (Bluesky) labels are translated to/from the fediverse's sensitive flag and content warnings. Blocking and muting is translated too, and works just like normal. Similarly, if you or an admin block an entire bridged network, that works just like blocking a native instance.

  Bridgy Fed also incorporates and obeys lower level mitigation techniques such as the fediverse’s authorized fetch aka secure mode. It always includes valid HTTP Signatures when fetching actors and other objects.

  For more background, see our content moderation policy and this blog post.

• I got suspended or moderated or labeled as spam, NSFW, etc, but I'm not! What do I do?

• Oh no, sorry! Bridgy Fed generally doesn't do any direct moderation or labeling itself. As described above, we primarily bridge the networks' own moderation activities and labels. If you bridge your account into another network, and you get suspended or moderated or labeled there, your best bet is to contact their support directly, eg the fediverse instance's admins or Bluesky moderation (background).

• How do I disable the bridge?

• If you're on the fediverse or the Atmosphere (Bluesky), and you've enabled this bridge and now want to disable it, block the Bridgy Fed bot user for the network you want to opt out of. For example, on the fediverse, block @bsky.brid.gy@bsky.brid.gy. On the Atmosphere, block @ap.brid.gy.

  (However, if you're on a Pixelfed instance, DM the word stop to @bsky.brid.gy@bsky.brid.gy instead. Pixelfed doesn't yet send the ActivityPub Block activity, so blocking won't work. Hopefully they'll fix that soon!)

  If you're on the web, email us from an address at your web site's domain to show that you own it, or you can put the text #nobridge in the profile on your home page and then update your profile on your user page.

  Once you've done this, Bridgy Fed will deactivate your bridged profile in that network, and it will no longer bridge any of your posts or interactions there.

  You can undo this later and reactivate bridging for your account, but depending on the network, not everything will be perfectly restored. For example, when you disable bridging into the fediverse, the bridged fediverse account is deleted and all followers are disconnected. If you later re-enable it, fediverse users will have to search for your account by address manually to find and follow it again.

• Why is Bridgy Fed chatting or DMing with me?

• Bridgy Fed sends a few different types of chat messages (aka DMs, or direct messages):

  • When you first enable it for your account.
  • When you first reply to a bridged account, but you haven't enabled the bridge yourself, so they won't see your reply.
  • If you haven't enabled the bridge, and someone on a different network requests that you enable it so they can follow you. (Bridgy Fed includes a link to their profile in this message.)
  • If someone who isn't bridged replies to you. The message will include link(s) that let you respond to the reply.
  • A confirmation or other reply when you message it to request that someone else enables the bridge.

  Bridgy Fed tries hard to avoid spamming. Apart from replying to your own messages, it will only send you at most one of each of these messages, ever.

  Also, chats with Bridgy Fed bot accounts are not monitored by a human. Feel free to file an issue in GitHub if you have a bug report or feature request!

• Is account migration supported?

• Yes!

  If you bridge your web site and then move to a different host, but keep the same domain, everything will keep working. Same if you bridge an Atmosphere (Bluesky) account and then migrate to a new PDS, or if you bridge a fediverse account and then migrate it to a different fediverse account. Spam filters don't apply, eg your new account doesn't have to be a week old. Your bridged accounts in other network(s) will switch to bridging from your new PDS or fediverse account.

  Also, if you're bridged to another network, you can later migrate your bridged account in that network out to become a native account, either on your settings page or with the migrate-to DM command.

  Also check out Bounce, our cross-network migration tool!

• Can I log into my bridged account and use it like a normal account?

• Sorry, no, Bridgy Fed doesn't support this yet.

• Can I use this to bridge two existing accounts that I already have?

• Sorry, no, Bridgy Fed doesn't support this. When it bridges one of your accounts into a new network, Bridgy Fed fully owns the bridged account in the new network. Fortunately, there are many other cross-posting and clients tools that can copy posts between existing accounts!




Using

• How do I get started?

• Here are instructions if you're coming from:

  • the web
  • the fediverse
  • the Atmosphere (Bluesky)
• Which accounts do I need?

• None! At least, no more than the accounts you already have. Bridgy Fed doesn't cross-post (ie copy posts) between separate accounts. Instead, it federates, or mirrors, your existing accounts into other networks.

  If you have a web site or blog, and you want it to cross-post to social networks, check out Bridgy classic!

• How do I update my profile?

• In general, Bridgy Fed updates your profile automatically. When you change your profile in one social network, Bridgy Fed detects the change and automatically updates it everywhere else it's bridged.

  If you want to refresh your profile manually, click the button on your user page. Bridgy Fed will update your profile and send it to any networks you're bridged into. (Only your profile, not your posts or other interactions.)

• I tried it, and it didn't work!

• Here are a few reasons Bridgy Fed might not currently bridge your profile or posts. If any apply, fix them, then try bridging your account again.

  • As basic spam filters, Bridgy Fed requires a couple things on your profile:
    • a profile picture
    • if your server advertises account age (like Mastodon), your account needs to be at least one week old
  • Bridgy Fed generally only bridges posts going forward; it doesn't backfill older posts from before you enabled it. If you want to see it bridge your posts, try a new one!
  • Bridgy Fed only bridges fully public posts and replies, not unlisted, quiet public, followers-only, mentioned-only, or otherwise non-public ones.
  • If you're on the fediverse, the Bridgy Fed bot account will follow you back. If your account is set to accept follows, did you accept it? If not, your instance won't send Bridgy Fed your posts, so they won't get bridged.
  • Have you blocked the Bridgy Fed bot account? If so, that disables the bridge for your account. Un-block it and then re-enable the bridge.
  • Bridgy Fed currently doesn't bridge posts if they're over two weeks old. This is largely because some fediverse servers, notably Mastodon, don't fully honor backdated posts and instead serve them in feeds as if they were new.
  • If you're looking at your bridged account in the fediverse, Bridgy Fed only delivers your posts, profile updates, etc. to fediverse instances where you have at least one follower. (This is how the fediverse works in general.)
  • If you're on the fediverse, your server might be blocking or limiting Bridgy Fed. Check your server's About page to see if bsky.brid.gy or brid.gy are in the Moderated servers section. If they are, you can ask your server admin to reconsider, and include a link to this page for more details.
  • If you're on the fediverse, and your username - ie the first part of your handle, before the middle `@` character - begins or ends with _, -, or ~, or contains any non-alphanumeric characters, ie anything other than A-Z a-z 0-9 _ - ~, Bridgy Fed can't currently bridge your account. Sorry. This may change in the future; follow the GitHub issue for details.
  • Bridged accounts can't be quote-posted on Mastodon yet, except by themselves. Bridgy Fed supports the fediverse's original quote posts, FEP-e232, but Mastodon designed a newer version, FEP-044f, that's more powerful but also much more complicated, so we haven't been able to prioritize it yet. (The one exception is self quote posts. Mastodon accepts those via FEP-e232, so when a bridged user quote posts themself, that works.)
  • We rate limit bridging activities (posts, replies, likes, reposts, follows, unfollows, deletes, etc) to one every 5 seconds per user. If you do things faster than that, we'll still bridge them all, they just get delayed.

  If none of that helps, check out your user page! It detects and describes common problems with your setup, and it shows your recent interactions and detailed logs.

• Can I see my account's status and recent activity?

• Definitely! Use this form to find your user page. It shows your account's current status in Bridgy Fed, recent interactions, remote follow UI, and links to your timeline feeds in various formats.

• How does my bridged account's follower count work?

• Follower counts are inexact. Unlike profiles and posts and other interactions, we don't try too hard to match bridged accounts' follower counts with their followers across all networks. If they don't exactly reconcile, that's normal, for many possible reasons. Don't worry about it.

• How do I @-mention a bridged user?

• The same way you @-mention people normally! Find them in your local social network, then @-mention them natively. No special syntax or anything else needed.

  (If they haven't enabled the bridge, then you won't be able to find them or @-mention them.)

• How do I delete a post?

• Just delete it normally! Bridgy Fed will detect that and delete it in every other network that it was bridged to.

• What happens when someone replies or interacts with me?

• If they're bridged into your network, you'll see the reply or interaction natively! Otherwise, if you're on a network that supports DMs/chat, Bridgy Fed will send you a DM every hour with replies and @-mentions from people who aren't bridged into your network. Make sure you're accepting DMs from the Bridgy Fed bot user, eg you're not blocking it, and if you only accept DMs from accounts you follow, that you're following it too. You can disable these notification DMs by replying with the text mute.

  Each notification link to an unbridged post will also include a respond link to a Bridgy Fed page that you can use to respond. You can like the post, repost it, reply to it, or block its author.

• How do I block someone in another network who's not bridged into mine?

• If you're on the web, the Atmosphere (Bluesky), Mastodon, or Pixelfed, you can log in and block them from the settings page.

  Otherwise, you can use the block DM command. First, find the Bridgy Fed bot account for the network they're in. Then, DM that account block [handle], where handle is the address of the user you want to block.

  For example, if you're on the fediverse, and you want to block @badguy.bsky.social on the Atmosphere, find the @bsky.brid.gy@bsky.brid.gy account and send it a DM with the text block badguy.bsky.social.

  If you change your mind, you can unblock them with the unblock command, eg unblock badguy.bsky.social.

• How do I subscribe to a blocklist?

• Blocklists are currently supported on the Atmosphere (Bluesky). If you're on another network and bridged into the Atmosphere, use the block DM command with a Bluesky (bsky.app) list URL to block that list. For example, to block this list, DM the text block https://bsky.app/profile/snarfed.org/lists/3m4qzag4fjg26 to the Bridgy Fed bot account @bsky.brid.gy.

  You can also subscribe to fediverse-style CSV domain blocklists. Subscribing to a domain blocklist will block bridged interactions with users on any domain on the list. This applies to fediverse instances, web sites, ATProto PDSes, domain handles, etc. To subscribe to a domain blocklist, choose one from the Domain blocklists drop-down on your settings page, or enter the CSV URL into the Block form there, or DM the URL to a Bridgy Fed bot account.

  (Note that Bridgy Fed can only use domain blocklists to prevent bridging direct interactions, and sometimes block affected users from seeing your posts. It doesn't create per-user blocks for every affected user, it can't entirely block people from interacting, and it can't always prevent affected users from seeing your posts in all cases.)

  If you change your mind, you can unblock a list with the unblock command, eg unblock https://bsky.app/profile/snarfed.org/lists/3m4qzag4fjg26.

• The *.brid.gy domain in my bridged account's handle is ugly. Can I get rid of it and use my own domain/web site instead?

• Yes! Many supported networks let you use your own domain as your handle one way or another. This takes a bit of technical setup with DNS or a web server, but it's very doable. Here are instructions for web sites and fediverse accounts bridged into the Atmosphere (Bluesky), and for web sites bridged into the fediverse.

• What commands can I chat or DM to the bot account?

• DM it help to see! Here's the full list:

  • start: enable bridging for your account
  • stop: disable bridging for your account
  • notify: enable notifications when someone who's not bridged replies to you, quotes you, or @-mentions you
  • mute: disable notifications
  • username [domain]: set a custom domain username (aka handle)
  • [handle]: ask it to DM a user to request that they bridge their account
  • did: get your bridged Atmosphere (Bluesky) account's DID (only supported with the Atmosphere bot)
  • block [handle or list URL, ...]: block one or more user who aren't bridged, and/or lists, on another network
  • unblock [handle or list URL, ...]: unblock one or more users who aren't bridged, and/or lists, on another network
  • migrate-to [handle]: migrate your bridged fediverse account out of Bridgy Fed to a native fediverse instance
  • migrate-to [PDS domain] [email address] [new handle] [password] [invite code (optional)]: migrate your bridged Atmosphere account out of Bridgy Fed to a native PDS
• I want to follow someone, but they're not bridged!

• Start a chat or DM with the Bridgy Fed account and send it their handle! Bridgy Fed will send them a message and say that you've requested that they enable the bridge.

  For example, if you're on the Atmosphere (Bluesky), and you want to follow the fediverse account @snarfed@indieweb.social, but they're not bridged, send an Atmosphere chat message to @ap.brid.gy with the text @snarfed@indieweb.social, and Bridgy Fed will send them a DM.

  Similarly, if you're on the fediverse, and you want to follow the Atmosphere account @snarfed.bsky.social, but they're not bridged, send a DM to @bsky.brid.gy@bsky.brid.gy with the text @snarfed.bsky.social, and Bridgy Fed will send them a chat message.

  Bridgy Fed will only message a given recipient once, the first time they're requested. If you or someone else request them again, Bridgy Fed won't message them again.

  Also, you can only request 10 users per day. Use them wisely!

  On the Atmosphere, Bridgy Fed has to poll for chat messages, so if you send it a message, it may not respond immediately. It will within a minute at most!

  Also, Atmosphere accounts default to only accepting DMs from people they follow. If people on the Atmosphere aren't seeing Bridgy Fed's DMs, this is probably why. They can fix that by changing that setting to allow DMs from all accounts. (We definitely know this is inconvenient and makes this feature less useful!)

  Here's an example of the exact text in the prompt DM:

  Hi! Ryan Barrett · snarfed.indieweb.social.ap.brid.gy is using Bridgy Fed to bridge their account from the fediverse into the Atmosphere (Bluesky) here, and they'd like to follow you. You can bridge your account into the fediverse by following this account. See the docs for more information.

  If you do nothing, your account won't be bridged, and users on the fediverse won't be able to see or interact with you.

  Bridgy Fed will only send you this message once.




From the fediverse

• How do I get started?

• To bridge your fediverse account into the Atmosphere (Bluesky) and interact with people there, log in here, then click the Enable button.

  Or, if login isn't supported for your fediverse server, search for and follow @bsky.brid.gy@bsky.brid.gy in the fediverse. That account will then follow you back. Accept its follow to make sure your fediverse posts get sent the bridge and make it into the Atmosphere. You can unfollow it afterward if you want, you'll still stay bridged. (Here's how to disable.)

  If your fediverse account is @[user]@[instance], your bridged account will have the handle [user].[instance].ap.brid.gy in the Atmosphere. For example, @snarfed@indieweb.social is bridged into the Atmosphere as @snarfed.indieweb.social.ap.brid.gy.

  If your fediverse username has _ (underscore) or ~ (tilde) characters, they're converted to - (dash) characters. For example, @a_b~c@my.social is bridged into the Atmosphere as @a-b-c.my.social.ap.brid.gy.

  Fediverse usernames that begin or end with _, -, or ~, or that contain any non-alphanumeric characters, ie anything other than A-Z a-z 0-9 _ - ~, are not currently supported. Sorry. This may change in the future; follow this GitHub issue for details.

  The Atmosphere limits profile bios to 256 characters, so if yours is longer in the fediverse, it will be truncated and ellipsized.

  You can also find and follow bridged Atmosphere accounts without bridging your own account, but they won't see your posts or interactions.

• How do I find a bridged Bluesky account?

• If a Bluesky account has enabled the bridge, it will appear in the fediverse as @[handle]@bsky.brid.gy. For example, @snarfed.bsky.social on Bluesky is bridged into the fediverse as @snarfed.bsky.social@bsky.brid.gy.

• I can't find @bsky.brid.gy@bsky.brid.gy on the fediverse!

• If you search for @bsky.brid.gy@bsky.brid.gy on your fediverse instance and you don't see any results, your server may be blocking Bridgy Fed. Check your server's About page to see if bsky.brid.gy or brid.gy are in the Moderated servers section. If they are, you can ask your server admin to reconsider, and include a link to this page for more details.

• How do I find a bridged web site?

• To follow a web site, first enter it here to make sure it's set up, then wait a minute, then search for @[domain]@web.brid.gy in your fediverse instance. For example, to follow nature.com, search for @nature.com@web.brid.gy.

  Bridged web sites appear in the fediverse as either @[domain]@[domain], @[domain]@web.brid.gy, or @[domain]@fed.brid.gy, depending on the fediverse server and whether the web site owner has connected their domain to Bridgy Fed. All bridged web sites behave the same in the fediverse; the different instances in their handles are purely cosmetic.

• Which stuff of mine from the fediverse will get bridged?

• Once you've enabled the bridge, anything that's fully public and interacts with Bluesky users. This includes your posts, replies, likes, and reposts if the original post was bridged. Posts on Bluesky are limited to 300 characters, so longer posts from the fediverse are truncated and ellipsized. Hashtags, links, link previews, images, videos, and even alt text are also included.

• I'm a fediverse instance admin. What do I need to know?

• Thanks for asking! Beyond what Bridgy Fed is and what it does, here's some useful info for fediverse instance admins.

  • Bridgy Fed is opt in. When a fediverse user enables it for a given network, eg Bluesky, it bridges their profile and posts and other interactions into that network giong forward. It doesn't bridge anything for users who haven't enabled it yet.
  • This means that fediverse users don't exist in Bluesky, and can't be followed or found in search there, unless they've enabled the bridge.
  • Users enable the bridge to Bluesky by following the @bsky.brid.gy@bsky.brid.gy user, and disable it by blocking that user. When they disable it, their profile and posts are all removed from Bluesky.
  • Atmosphere (Bluesky) users can also bridge themselves into the fediverse. Unbridged fediverse users may follow them and interact with them, but those follows and interactions aren't bridged back into Bluesky.
  • Only fully public posts are bridged into Bluesky. Unlisted aka quiet public, followers-only, and private mentions aka DMs are never bridged.
  • Replies, reposts, and quote posts are only bridged if the original post being replied to, reposted, or quote posted was also bridged.
  • Blocks are bridged too. If a fediverse user blocks a bridged Bluesky user, it works just like blocking a normal fediverse user. Bridgy Fed also converts it to a Bluesky block on that end.
  • Reports aka Flags are similarly bridged. If a fediverse user reports a bridged Bluesky user or post, Bridgy Fed sends it to Bluesky's moderation service as a report. The Bluesky team is then able to act on that user or post just like normal.
  • In general, bridged Bluesky users in the fediverse work just like normal fediverse users. All admin-level and user-level tools apply to them like you'd expect.
  • If a user enables the bridge and it doesn't work for them, point them to our troubleshooting docs.
  • Limiting aka silencing brid.gy or its subdomains works, but will make it more difficult for your users to enable the bridge. We also hear that limiting Bridgy Fed can result in confusing visibility and behavior that appears buggy. We don't fully understand the details here yet, or whether we can do much about it.
  • If you want, you can set your instance up to automatically enable the bridge for new users, and even automatically give them custom domain handles on Bluesky.

  Here are some details on our federation, ActivityPub, and Webfinger support.

  • Each bridged network has its users on a different brid.gy subdomain, eg bsky.brid.gy for Bluesky and web.brid.gy for web sites. You can block specific networks by blocking their subdomain, but you'll still need to allow fed.brid.gy and brid.gy for the bridge to work at all.
  • Bridgy Fed's instance actor for signing GETs (ie authorize fetch) is https://fed.brid.gy/fed.brid.gy aka @fed.brid.gy@fed.brid.gy.
  • Some web sites bridged into the fediverse will have Webfinger addresses on their own domains, eg @snarfed.org@snarfed.org. Webfinger requests to those domains redirect to fed.brid.gy and are served there.
  • Bridged ActivityPub actors are type: Person. Bot actors like @bsky.brid.gy@bsky.brid.gy and @fed.brid.gy@fed.brid.gy are type: Service.
  • When a fediverse user opts into the bridge, their profile and posts will be indexed and searchable in Bluesky's search even if they have the discoverable or indexable flags set to false. Bluesky doesn't currently have a way to opt individual users out of search.
  • Likewise, Bluesky users are automatically included in Bluesky's search index. There's no way for individual users to opt out. So, when a Bluesky user bridges to the fediverse, we carry over that implicit consent and set their discoverable and indexable flags to true.



To the fediverse

• How do I verify my profile links (ie get green checks) in Mastodon?

• Mastodon's verified profile links with ✅ green checks are fun! If you're bridged into the fediverse, and you have a web site, follow these steps to get one:

  • Add a link to your web site to the account you've bridged to the fediverse. (If you bridged your web site itself, skip this.)
  • If you're coming from Bluesky: add a rel=me link (it can be invisible) to your web site's home page that points to https://bsky.brid.gy/ap/[DID], where [DID] is your Bluesky account's DID. For example:.

    <a rel="me" href="https://bsky.brid.gy/ap/did:plc:fdme4gb7mu7zrie7peay7tst" />
    

  • If you're coming from the web: add a rel=me link (it can be invisible) to your web site's home page that points to https://web.brid.gy/r/https://[DOMAIN]/, where [DOMAIN] is your site's domain. For example:

    <a rel="me" href="https://web.brid.gy/r/https://example.com/" />
    

  • On your Bridgy Fed user page, click the button to update your profile, then copy your fediverse handle.
  • Log into any Mastodon instance where you have an account.
  • Search for your fediverse handle.
  • Click on your bridged fediverse account in the search results.
  • Wait a few minutes, then refresh the page. You should see a green check on the profile link for your web site.

  When you're logged into a Mastodon instance, searching for your bridged web site triggers that instance to check and verify its profile link(s) in the background. This only works when you're logged in with a native Mastodon account. Also, each instance does this independently; verified links are not synched across instances.

• Can I use my own domain as my fediverse handle?

• If you're bridging a web site, yes! By default, fediverse handles for web sites use web.brid.gy as their instance, eg @mysite.com@web.brid.gy, but you can change that to your own domain. It takes a bit of setup and technical know-how, but it's very doable.

  First, your domain needs to serve HTTP requests. You don't need an actual web site, but you do need a minimal web server.

  Second, your web server needs to support SSL. Bridgy Fed uses your domain as your identity, so it depends on SSL to prove that you own it.

  Lastly, your web server needs to redirect a couple URL paths, including query parameters, to the same paths on https://fed.brid.gy/:

/.well-known/host-meta
/.well-known/webfinger

Here are instructions for a few common web servers:

• WordPress (self-hosted): install the Safe Redirect Manager plugin, then add these entries:

  /.well-known/host-meta* => https://fed.brid.gy/.well-known/host-meta*
/.well-known/webfinger* => https://fed.brid.gy/.well-known/webfinger*
• Known or Drupal: follow the Apache or nginx instructions below.
• Apache: add this to your .htaccess file:
  

  RewriteEngine on
  RewriteBase /
  RewriteRule ^.well-known/(host-meta|webfinger).* https://fed.brid.gy/$0  [redirect=302,last]

  (RewriteEngine on is optional if you already have it earlier in your .htaccess. RewriteBase / is optional if you don't have any other RewriteBase directives, or if you put this RewriteRule inside an existing RewriteBase / section.)
• nginx: add this to your nginx.conf file, in the server section:
  

  rewrite ^/\.well-known/(host-meta|webfinger).* https://fed.brid.gy$request_uri? redirect;

• Netlify: add this to your netlify.toml file.

  [[redirects]]
    from = "/.well-known/host-meta*"
    to = "https://fed.brid.gy/.well-known/host-meta:splat"
    status = 302
  [[redirects]]
    from = "/.well-known/webfinger*"
    to = "https://fed.brid.gy/.well-known/webfinger"
    status = 302
    

• Will I show up in fediverse search engines and indexes?
• If you're coming from a network with built in search that users can't opt out of, like Bluesky, or that allows indexing by default, like the web - robots.txt notwithstanding - then yes. People on those networks already implicitly consented to indexing when they created their accounts, so we carry that consent over to the fediverse by setting their discoverable and indexable flags to true.
• I disabled my bridged profile, or deleted a post, but it's still visible in the fediverse!

• Sadly, this is a somewhat inherent part of the fediverse itself. When you disable the bridge for your account, Bridgy Fed sends Deletes to every fediverse instance where you had a follower, but it doesn't currently know about other instances that may have loaded and cached your profile. Same with posts bridged into the fediverse that you later delete. Those cached profiles and posts will eventually disappear over time.

• Mastodon is showing bridged posts in the wrong order!

• This is an unfortunate Mastodon quirk. All posts bridged to the fediverse have the correct timestamps, and posts in threads are connected in the right order, but Mastodon instances don't use those to sort posts in timelines. Mastodon sorts based on when it first received each post. This is usually chronological, but not always, since the internet isn't always perfectly reliable. Network hiccoughs, retries, out-of-order delivery, internal processing delays, asynchronous background processing, etc.

  This is only a problem in timelines and feeds. Replies should still show up in the right order when you view a post or thread.

  Background in these GitHub issues.

• Could other networks' instances get their own brid.gy subdomains, so that admins can federate with or block them individually?

• This is a great idea! It's difficult to implement technically - I'd need to build and run my own DNS server with custom behavior for resolving multi-level wildcard records - but it's definitely doable.

  However, servers and domains on other networks are very different from fediverse instances:

  • Atmosphere (Bluesky) PDSes are similar to shared web hosts; they're more generic and interchangeable than fediverse instances. They don't define affinity groups, user-visible communities, or moderation boundaries. It's not clear that they're useful for domain level federation decisions like fediverse instances are.
  • IndieWeb sites generally represent a single person. They're often domains, but when they're subdomains, eg on wordpress.com or blogspot.com, those are often shared hosting platforms that don't define clear communities or moderation boundaries either.

  Another difficulty is that accounts on Bluesky have long-lived, server-independent ids. If we used a Bluesky user's PDS domain in their fediverse handle, that handle would change every time they migrated to a new PDS, and they'd lose all of their followers and followings, even though their Bluesky account ID itself hadn't changed.




From Bluesky

• How do I get started?

• To bridge your Bluesky account into the fediverse and interact with people there, log in here, then click the Enable button. Alternatively, you can bridge your account by following @ap.brid.gy on Bluesky. You can unfollow it afterward if you want, you'll still stay bridged. (Here's how to disable.)

  After a few minutes, your Bluesky account will appear in the fediverse as @[handle]@bsky.brid.gy. For example, @snarfed.bsky.social on Bluesky is bridged into the fediverse as @snarfed.bsky.social@bsky.brid.gy.

  Alternatively, you can find and follow bridged fediverse accounts without bridging your own account, but they won't see your posts or interactions.

• How do I find a bridged fediverse account?

• Search in Bluesky for their fediverse address (eg @snarfed@indieweb.social) or profile URL (eg https://indieweb.social/@snarfed), and then click the People tab. If they've enabled the bridge, they'll show up there.

  Bridged fediverse accounts will appear in Bluesky as @[user].[instance].ap.brid.gy. For example, @snarfed@indieweb.social is bridged into Bluesky as @snarfed.indieweb.social.ap.brid.gy.

• How do I find a bridged web site?

• To follow a web site, first enter it here to make sure it's set up, then wait a minute, then search for it in Bluesky as [domain].web.brid.gy. For example, nature.com is bridged into Bluesky as nature.com.web.brid.gy.

• Can I use Bluesky's reply controls?

• Yes! Bluesky's reply controls apply to accounts bridged from the web and the fediverse as well as to native Bluesky accounts. Those platforms don't have reply controls, so if you bridge your Bluesky account and post with reply controls, people on the fediverse and the web will still be able to reply, but those replies won't show up in Bluesky.

• Is Bridgy Fed subject to Bluesky PBC's moderation? If Bluesky bans someone, and they move to a different PDS, can they still use Bridgy Fed?

• No, and yes. Bluesky PBC (the company) controls which accounts can use their servers (PDS, relay, appview), but they don't control everything else on the AT Protocol network. Bridgy Fed operates at the protocol level, not the API level, so if Bluesky PBC moderates or bans an account, Bridgy Fed can still see and bridge that account and its activity.




To Bluesky

• Which stuff of mine can get bridged into Bluesky?

• Bluesky is just one of many apps on the AT Protocol network. Bridgy Fed currently supports these apps and compatible clients:

  • Bluesky (bsky.app) profiles, follows, posts, images, videos, hashtags, @-mentions, and content warnings. Also replies, likes, and reposts if the original post was already bridged.

  • standard.site publications and documents, usable in apps like Leaflet, Pckt, Offprint, Blento, etc.
  • ...and more to come!
• Which stuff can't get bridged into Bluesky?

• Polls, edits/updates, or (most) GIFs.

• What happens when I report a bridged Bluesky user?

• Bridgy Fed sends your report to the Bluesky team's official moderation service, which handles it, and takes action if necessary, just like with native Bluesky accounts.

  Also see Bridgy Fed's moderation policy and functionality.

• I edited a post, but it didn't get edited in Bluesky!

• Bluesky doesn't support editing posts right now. Bridgy Fed currently sends edits via the underlying AT Protocol, which does currently support them, but the Bluesky app itself doesn't. Hopefully eventually!

• Can I use my own domain as my Bluesky handle?

• Yes! Just follow these three steps:

  1. Get your bridged account's DID. You can DM the text did to the Bluesky Bridgy Fed bot account (eg @bsky.brid.gy@bsky.brid.gy), or go to your user page and click the next to to your bridged Bluesky account link.
  2. Connect your domain to your bridged Bluesky account. You can do this with DNS (just steps 5 and 6) or with HTTPS. Once you're done, check your work here.
  3. If you're on the fediverse, log in here and enter your domain in the Set Bluesky handle form. Or, if your account isn't supported for login, send a DM to @bsky.brid.gy@bsky.brid.gy with the text username [domain] (eg username my.site.com). If you're bridging a website, click the button on your user page.

  If you want to undo this later and change back to your original default handle, you can do it the same way. For example, if you're @user@instance.com on the fediverse, DM username user.instance.com.ap.brid.gy, or enter user.instance.com.ap.brid.gy into the form on the settings page.

• Can I verify my web site or domain with standard.site?

• standard.site has a mechanism for web sites to verify themselves. If you bridge a web site to Bluesky, you can do this verification by redirecting the /.well-known/site.standard.publication path on your web site to https://fed.brid.gy/.well-known/site.standard.publication?protocol=[protocol]&domain=[domain]. Replace [domain] with your web site's domain and [protocol] with web if you're bridging a web site, ap if you're bridging a fediverse account.

  For example, if your web site is https://example.com/, and you're bridging a fediverse account, you'd redirect https://example.com/.well-known/site.standard.publication to https://fed.brid.gy/.well-known/site.standard.publication?protocol=ap&domain=example.com.

  This is similar to redirecting a web site's WebFinger to Bridgy Fed. More details and examples there.

  If you're on the fediverse, your account also needs to be the web site's root actor. Specifically, your ActivityPub actor needs your site's home page in its url field, eg "url": "https://example.com/", and when Bridgy Fed fetches your site's home page as ActivityPub, eg with the Accept: application/activity+json header, it should return that same actor. (This is just an example; Bridgy Fed's actual Accept header is more complicated.)

  Many ActivityPub-enabled web servers support this, but not all. Ghost is one example that doesn't. Background on GitHub. We'd love to expand this eventually to support them too!

• Can I link my bridged web pages or articles to their standard.site documents?

• Yes! Beyond verifying web sites, standard.site also has a mechanism to link individual web pages to their standard.site documents. You can do this by including a <link> element in your web page's HTML that points to its bridged at:// URI.

  First, to get a bridged web page's at:// URI, construct a Bridgy Fed URL to convert it to Bluesky. For example, for an ActivityPub Article with id http://instan.ce/article, the Bridgy Fed Bluesky URL would be https://ap.brid.gy/convert/bsky/http://instan.ce/article.

  Then, fetch that URL and look at the response's Link header. It will be the bridged at:// URI of the site.standard.document record, eg at://did:plc:abc123/site.standard.document/xyz. Add that URI to your web page's HTML in a <link> element like this:

  <link rel="site.standard.document" href="at://did:plc:abc123/site.standard.document/xyz" />
  

• How can I see the full text or original URL for a bridged post?

• If a post bridged into Bluesky is truncated, it will include an embed with a link to the original post. You can also find the original post link indirectly by opening the author's profile and following the link in their bio to their original account.

  For developers, Bridgy Fed includes the full text and URL for bridged posts and profiles inside their AT Protocol records. Bridged app.bsky.actor.profile records have bridgyOriginalDescription and bridgyOriginalUrl fields, and bridged app.bsky.feed.post records have bridgyOriginalText and bridgyOriginalUrl fields. Here's an example:

  {
    "$type": "app.bsky.feed.post",
    "text": "This is a very long post that got cut off and ...",
    "bridgyOriginalText": "<p>This is a very long post that got cut off and has more to say.</p>",
    "bridgyOriginalUrl": "https://indieweb.social/@snarfed/abc123",
    "..."
  }
  

• Why can't I see a video?

• Bluesky currently limits videos to 60 seconds, 100MB, and .mp4, .mpeg, .webm, or .mov. If you're seeing a "Video not found. Retry" error, the original video may not satisfy those requirements.

• My images or videos are blank in Bluesky!

• This usually means that the server hosting your images is blocking or otherwise not serving them to Bluesky's CDN. To confirm this, open an affected post in bsky.app, then open one of the blank images in a new browser tab. (Right click, Open image in new tab, or something similar.) If it shows the error Source image is unreachable instead of the image, your server is blocking Bluesky's CDN. GoToSocial is one known example; here's a workaround. Otherwise, check your Cloudflare, CDN, server or host settings, they might be configured overly aggressively to block bots. More background.

• My images are broken or corrupted in Bluesky!

• The Bluesky CDN has an undocumented limit of 10MB for images. If you post images larger than that, they may look broken or corrupted in Bluesky. We bridge them anyway, which isn't ideal, but so far we've chosen to do that instead of silently dropping these posts. We're open to feedback!




From the web

• How do I get started?

• Your web site will need either microformats and webmention support, or an Atom or RSS feed discoverable from your home page, so that Bridgy Fed can find your posts. When you're ready, connect your site, then try following your site from the fediverse. If that looks good, start following other fediverse users!

  We recommend that your site supports webmentions. You can see a notifications feed of your interactions from other networks - replies, reposts, likes, etc - but to get them back to your site, it needs to support webmentions. Check out the IndieWeb wiki for instructions for your web server and examples of existing projects that support microformats and webmentions.

  If your site serves WebFinger requests itself, Bridgy Fed won't support it. This generally happens when your site is already a fediverse instance or has its own fediverse integration. If Bridgy Fed tried to work in these cases, it might conflict with your existing ActivityPub server.

• Where does my profile info come from?

• Your site's bridged profile can come from a few different things on your home page. Here's what Bridgy Fed looks for, in order of preference:

  • A microformats2 representative h-card on your site's home page.
  • Twitter card, Open Graph, and related meta tags in your HTML.
  • Basic HTML meta tags like <title> and <meta name="description">.

  Here's a minimal example of h-card HTML that sets your name and a profile picture:

  <span class="h-card">
    <a class="u-url" rel="me" href="/">Alice Foo</a>
    <img class="u-photo" src="/me.jpg" />
  </span>
  

  You can use indiewebify.me to check your site's h-card interactively, but note that that doesn't check that it's representative. In the common case, this just means that your h-card needs a link to your home page with the u-url class. See the representative h-card spec for more details.

  If you want to set a header image, add a u-featured image to your h-card, eg:

  <img class="u-featured" src="/my-header.png" />
  

  Your Bluesky handle will be yourdomain.com.web.brid.gy.

  By default, your fediverse address will be @yourdomain.com@yourdomain.com. Many services (eg Mastodon) default to only showing the username, so this generally shows up as just @yourdomain.com in posts, and the full address appears on hover.

  We recommend this for simplicity and predictability, for everyone else as well as you, but if you want a different username, you can set it by adding an acct: u-url link inside your h-card with username@yourdomain.com, eg:

  <a class="u-url" href="acct:alice@yourdomain.com"></a>
  

• How does Bridgy Fed find my posts?

• Bridgy Fed can discover web site posts via webmentions and Atom/RSS feeds.

  The first time someone follows a web site via Bridgy Fed, it looks for an Atom or RSS feed. If it finds one, it extracts and bridges those posts, then periodically checks for new posts.

  Instead of waiting for that periodic poll, you can bridge a new or updated post immediately by including microformats in your HTML and sending Bridgy Fed a webmention. Include a link to https://fed.brid.gy/ in your post, and if your web server supports webmentions, it should send one automatically. Alternatively you can send one manually. (Note that triggering via webmention requires your post HTML to be marked up with microformats.)

  Once you send Bridgy Fed a webmention from your site - any webmention! - it will stop reading posts from your Atom or RSS feed, and expect webmentions instead for all posts in the future. You can use this to prevent automatically bridging all posts, and instead choose proactively which of your posts to bridge.

  Here's example HTML for a post:

  <div class="h-entry">
    <p class="e-content">Two naked tags walk into a bar. The bartender exclaims, "Hey, you can't come in here without microformats, this is a classy joint!"</p>
    <a class="u-bridgy-fed" href="https://fed.brid.gy/" hidden="from-humans"></a>
  </div>
  

  The link to fed.brid.gy may be blank. If so, it should include the hidden attribute to be kind to screen readers and keyboard navigation users. The u-bridgy-fed class is optional but useful in some cases to prevent microformats2 parsers from interpreting the link as an implied u-url.

• How does it decide which parts of my posts to include?

• For RSS and Atom, Bridgy Fed uses those formats' native elements to extract your post's title (if any), URL, author, tags, date and time, etc.

  For webmention-based posts, Bridgy fetches your HTML and parses its microformats, notably the e-content and (legacy) entry-content classes. It also understands and translates other classes like u-like-of, u-repost-of, u-in-reply-to, u-follow-of, u-photo, u-video, p-category, and more.

  Otherwise, Bridgy Fed uses Twitter card, Open Graph, and related meta tags in your HTML.

  Bridgy Fed includes your posts' full content when possible, and only truncates if necessary. However, not all bridged networks currently show the full content of all posts.

  For example, text-based posts fall into two broad buckets: short notes for microblogging and longer articles for long-form articles and blog posts. In the IndieWeb, we differentiate based on whether the post has a title: articles generally have titles, notes don't.

  In the fediverse, Mastodon currently shows the full text of notes, but for articles, it only shows their titles and a link to the full article. This is because it and most other fediverse apps are designed primarily for smaller notes, not longer articles.

  Also, Mastodon preserves HTML links and line breaks and some formatting, but not all. Other fediverse servers vary in their HTML handling.

• What's up with the visible fed.brid.gy links in my fediverse posts?

• These can happen for a couple reasons. For articles, this is expected behavior, as described above. The link is a Bridgy Fed URL that redirects to the original post on your web site. This is because Mastodon requires ActivityPub (ie fediverse) object URLs to use the same domain that serves them, which in this case is fed.brid.gy. We know it's awkward; sorry for the ugliness!

  Otherwise, this may be the invisible fed.brid.gy link that's required to trigger Bridgy Fed. Mastodon will show a preview of links even if their text is blank, so if your link is inside your e-content microformats2 element, that's probably what's happening. You can prevent that by moving it outside of e-content. It can go anywhere in your HTML!

• How do I reply to a fediverse or Bluesky post?

• Replies require microformats and must be triggered via webmention. Put the reply in a new post on your web site, and include a link to the post you're replying to with class u-in-reply-to, as if you were publishing a normal IndieWeb reply. For example:

  <div class="h-entry">
    <p class="e-content">Highly entertaining. Please subscribe me to your newsletter.</p>
    <a class="u-in-reply-to" href="https://indieweb.social/@tchambers/109243684867780200"></a>
    <a class="u-bridgy-fed" href="https://fed.brid.gy/" hidden="from-humans"></a>
  </div>
  

• How do I like or repost a fediverse or Bluesky post?

• Likes and reposts require microformats and must be triggered via webmention. They're almost exactly the same as replying. The only difference is that you use u-like-of for a like or u-repost-of for a repost.

  <a class="u-like-of" href="https://indieweb.social/@tchambers/109374703563569354"></a>
  

  <a class="u-repost-of" href="https://cosocial.ca/@evan/110290575042195305"></a>
  

• How do I follow someone?

• If your web site supports IndieAuth, go to your user page, click the Following link, then enter the address of the account you want to follow.

  You can also follow someone by posting an IndieWeb follow on your site, including the u-follow-of microformats2 class, and sending a webmention to Bridgy Fed. Your site may do that automatically if it supports webmentions. For example:

  <div class="h-entry">
    I'm now following <a class="u-follow-of" href="https://mastodon.social/@adactio">@adactio@mastodon.social</a>!
    <a class="u-bridgy-fed" href="https://fed.brid.gy/" hidden="from-humans"></a>
  </div>
  

  This method doesn't require IndieAuth, and it can be automated.

• How do I unfollow someone?

• Go to your user page, click the Following link, find the account you want to unfollow, and click the X next to their address. Like following, this requires your web site to support IndieAuth.

• How do I include an image in a post?

• If you're using microformats and webmentions, put the <img class="u-photo"> class on the image in your post. For example:

  <img class="u-photo" src="/full_glass.jpg" alt="a drink" />
  I love scotch. Scotchy scotchy scotch.
  

• How do I include a video in a post?

• If you're using microformats and webmentions, put the <video class="u-video"> class on the video in your post. For example:

  <video class="u-video" src="/dancing.mp4"></video>
  Dancing dancing dancing
  

• How do I use hashtags?

• For RSS, use the <category> element.

  For Atom, use the <atom:category> element.

  For webmention and microformats2, use p-category and link the hashtag to a fully qualified URL. (Any URL you want!) Fediverse sites like Mastodon will generally rewrite the link to point to a search for that hashtag on the local instance. For example:

  <div class="h-entry">
    <p class="e-content">
      chasing the fun laser
      <a href="https://indieweb.social/tags/caturday" class="p-category">#caturday</a>
    </p>
  </div>
  

  The leading # character on the hashtag text is optional. If you don't include the hashtag in e-content, or include it but not inside an <a> link, fediverse sites won't add the hashtag text or link themselves, but your post will still be indexed in searches for that hashtag.

• How do I @-mention someone?

• @-mentions require microformats and must be triggered via webmention. Include a link to the user's profile in your post's content with an @ character at the beginning of the link text. For example:

  Hi <a href="https://mastodon.social/@adactio">@adactio</a>!
  

  The link and text are both necessary!

• How do I edit an existing post?

• Edits must be triggered via webmention. Edit the post on your web site, then send a webmention to Bridgy Fed for it. Bridgy Fed will refetch the post and updated it everywhere it was originally bridged.

• How do I delete a post?

• Deletes must be triggered via webmention. First, delete the post on your web site, so that HTTP requests for it return 410 Gone or 404 Not Found. Then, send another webmention to Bridgy Fed for it. Bridgy Fed will refetch the post, see that it's gone, and delete it in every network where it was bridged.

• Can I publish only one part of a page?

• If it's not your home page (ie path /), and the HTML element you want to publish has its own id, then sure! Put the id in the fragment of the URL that you publish. For example, to publish the bar post here:

  <div id="a" class="h-entry">foo</div>
  <div id="b" class="h-entry">bar</div>
  <div id="c" class="h-entry">baz</div>
  

  ...add the id to your page's URL in a fragment, e.g. http://site/post#b here.

• How do replies, likes, and other interactions show up on my site?

• To receive likes, reposts, replies, @-mentions, and follows from other networks, make sure your site accepts webmentions! Bridgy Fed translates those interactions and sends them to your site as webmentions. The source URL will usually be a proxy page on a subdomain of brid.gy. For best results, make sure your webmention handler detects and handles u-url links.

• How do I read my timeline/feed?

• Your user page has links to your timeline/feed, ie posts from people you follow, in HTML, Atom, and RSS formats. Add them to your feed reader or read them in your browser!

  (Secret pro tip! Add &quiet=true to the end of any Bridgy Fed feed URL to omit likes, reposts, and follows, and only show original posts and mentions.)

• Are there notifications?

• Yes! Your user page has a feed of your notifications - mentions, replies, likes, reposts, follows, etc - in HTML, RSS, and Atom formats, which you can subscribe to in any reader. (And &quiet=true - see above - works with these feeds too.)

• How can people find and follow me?

• They can search for your web site! Often you can enter your domain, eg yourdomain.com, in any fediverse or Bluesky search box. If that doesn't work, try your full address, either @yourdomain.com@yourdomain.com or @yourdomain.com@web.brid.gy in the fediverse and yourdomain.com.web.brid.gy in Bluesky.

  Your user page has a Followers link that shows you all of your followers. It has a "remote follow" form where people can enter their fediverse address and follow you directly.

• How can I see what my posts look like on other networks?

• On Bluesky, just check out your bridged profile!

  In the fediverse, it varies by server. For Mastodon, open your list of followers in Bridgy Fed and click on one to open their profile. Then, inside that Mastodon instance, search for your site's address, click on it in the search results, and you'll see your fediverse profile and all of your posts that were delivered to that instance. This may not be all of them, depending on how long and when people on that instance have been following you.

  This general process should often work in other fediverse servers too.

  Note: in Mastodon, each of your posts on a given instance will have a permalink inside that instance, eg mastodon.social/@snarfed.org@snarfed.org/109729052169033033, but those permalinks only go to Mastodon if you're logged into that instance. If you're not, they redirect to the original post on your site.

• Can I make my posts show up when people search for their URLs in the fediverse?

• Yes! Add this line of HTML to each post that you publish with Bridgy Fed and want to be searchable, replacing [URL] with that post's URL:

  <link rel="alternate" type="application/activity+json" href="https://fed.brid.gy/r/[URL]">
  

  Search is limited in Mastodon and much of the overall fediverse, so this won't index the full text of your posts, but it will make them show up in search results when you search for your post's full URL, which people commonly do in the fediverse to find and interact with posts.

• Can I verify my web site and use my domain as my handle on other networks?

• Yes! By default, your web site's bridged handle on other networks includes web.brid.gy, eg @yoursite.com@web.brid.gy, and your display name includes an [Unofficial] suffix. You can remove these by verifying your web site with Bridgy Fed and customizing your bridged handle. Here are instructions for fediverse handles and Atmosphere (Bluesky) handles.




Developers and admins

• Does Bridgy Fed have an API? Can I integrate my client or service or other tool with it?

• Yes! Bridgy Fed is a first class participant in the networks and protocols it supports, so for most purposes, we recommend that you interact with it natively via those protocols. However, if you want to go the extra mile, there are ways to make your project Bridgy Fed aware and improve your users' experience.

  The main thing we recommend is to use account links and post links, small bits of metadata that point to a given account or post on other networks. You can look for these inside objects when you fetch or receive them, and if you create or edit accounts and posts, you can add them yourself. Specifically:

  • When you see a new account, check whether it has any account links. If it does, show those links to the user.
    • Bonus: include the logo for each linked account’s network.
    • Bonus: fetch the linked account(s) and check that they have link(s) back. Include user-visible indicators on the links that verify.
  • Do the same for posts and post links.
  • Let your users set their own account links (aka aliases).
  • If you cross-post or bridge, set account and post links automatically.
  • If an account or post specifies its canonical version, prefer to fetch and render that version, since it will usually have the highest fidelity.
  The exact metadata for account and post links varies by network. Read on for details.
• How can I tell if an account is bridged from another network?

For an ActivityPub actor, check its alsoKnownAs field. If it's bridged from elsewhere, that field will have its native id as a URI. For example, an account bridged from Bluesky will have an at:// URI with its DID:

{
  "id": "https://bsky.brid.gy/ap/did:plc:3ljmtyyjqcjee2kpewgsifvb",
  "alsoKnownAs": ["at://did:plc:3ljmtyyjqcjee2kpewgsifvb"],
  ...

Similarly, a bridged web site will have its home page URL:

{
  "id": "https://fed.brid.gy/snarfed.org",
  "alsoKnownAs": ["https://snarfed.org/"],
  ...

Bluesky is similar. If a Bluesky user is bridged from elsewhere, its native id will be in alsoKnownAs in the user's DID document, eg:

{
  "id": "did:plc:bg5udl25mvzg3rt7l5n2hzet",
  "alsoKnownAs": ["https://indieweb.social/users/snarfed"],
  ...

On the web, h-cards for bridged users have their native id in the microformats2 uid property:

<span class="p-author h-card">
  <data class="p-uid" value="https://indieweb.social/users/snarfed"></data>

You can also use rel=alternate and rel=me to discover fediverse accounts that are associated with a web site, either bridged or otherwise.

• How can I tell if an account is bridged to another network?

Right now, this isn't as clean as detecting accounts bridged from other networks, since we generally don't have access to add metadata to native accounts. Currently, you can check if a native account is bridged elsewhere by fetching its Bridgy Fed user page, eg:

• https://fed.brid.gy/web/snarfed.org for a web site
• https://fed.brid.gy/ap/@snarfed@indieweb.social for a fediverse account
• https://fed.brid.gy/bsky/snarfed.bsky.social or https://fed.brid.gy/bsky/did:plc:3ljmtyyjqcjee2kpewgsifvb for a Bluesky account



If fetching that URL returns HTTP 200, the account is bridged. If it returns HTTP 404, it's not.

• How can I tell if a post was bridged from another network?

• On the fediverse, look for a FEP-fffd proxy link in the object's url field, ie an element with rel=canonical or rel=alternate. For example, this reply was bridged from Bluesky:

  {
    "type": "Note",
    "id": "...",
    "url": [
      "https://bsky.app/profile/snarfed.bsky.social/post/3lvcb3tswns26",
      {
        "type": "Link",
        "rel": "canonical",
        "href": "at://did:plc:3ljmtyyjqcjee2kpewgsifvb/app.bsky.feed.post/3lvcb3tswns26",
      },
    ],
    ...
  

  On the web, check if the post's microformats2 uid is on a brid.gy subdomain. If so, its original native id will be the last part of the path, after /convert/[protocol]/.

  For example, https://bsky.brid.gy/convert/ap/at://did:plc:3ljmtyyjqcjee2kpewgsifvb/app.bsky.feed.post/3lhputf77w22j is the Bridgy Fed ActivityPub id for a Bluesky post bridged into the fediverse. Its original Bluesky URI is at://did:plc:3ljmtyyjqcjee2kpewgsifvb/app.bsky.feed.post/3lhputf77w22j.

  You can also use rel=alternate and rel=canonical to discover other versions of a post in the fediverse and elsewhere.

  Bluesky doesn't have a standard way to do this yet. For now, Bridgy Fed uses the bridgyOriginalUrl field in the Bluesky post record; it will have the post's id in its native protocol. For example, this post was bridged from the fediverse:

  {
    "$type": "app.bsky.feed.post",
    "text": "hi @shnarfed"
    "bridgyOriginalUrl": "https://indieweb.social/@snarfed/114348129599184925",
    "bridgyOriginalText": "<p>hi <a href="https://threads.net/@shnarfed/" class="u-url mention">@shnarfed</a></p>",
    ...
  

• How can I tell if a post was bridged to another network?

• To see if Bridgy Fed bridged a native post (or any object) from one network to another, construct and fetch a Bridgy Fed URL with this format:

  https://[FROM].brid.gy/convert/[TO]/[ID]
  

  ...where [ID] is the post's id in its native network, and [FROM] and [TO] are Bridgy Fed network labels:

  Network	Label
  Web	web
  ActivityPub	ap
  ATProto	bsky
  Nostr (future)	nostr
  Farcaster (future)	fc

  For example, this fediverse post's ActivityPub id is https://indieweb.social/users/snarfed/statuses/116024251702608666. To see if Bridgy Fed bridged it to Bluesky, fetch this URL:

  https://ap.brid.gy/convert/bsky/https://indieweb.social/users/snarfed/statuses/116024251702608666
  

  If it was bridged, the response will be HTTP 200 with the converted object in the destination network's format, and the id of the bridged object in the Link HTTP header. In this example, the response body is the Bluesky app.bsky.feed.post record, and the Link header contains its at:// URI, eg:

  Link: <at://did:plc:bg5udl25mvzg3rt7l5n2hzet/app.bsky.feed.post/3me75t7irum22>; rel="self"
  

• Can I get additional metadata about a bridged account or post?

• On Bluesky, look for the bridgyOriginalUrl field described above, which links to the original native post. There's also a bridgyOriginalText field, which contains the original post's full text, before truncation.

  For posts bridged to the fediverse or the web, we translate everything to standard ActivityStreams 2 fields and microformats2 properties, respectively, so we don't need custom fields like for Bluesky.

• As a server admin, can I automatically enable the bridge for new users?

• Yes! On Bluesky and the fediverse, you can enable the bridge for a user by having them follow @ap.brid.gy or @bsky.brid.gy@bsky.brid.gy, respectively. Likewise, you can disable the bridge for a user by having them block that account. Your users will still be able to opt in or out individually, of course.

  If you do this, we strongly recommend and expect that you only do it for new users, not existing users, and that you tell new users loudly during the signup flow that they'll be bridged. If you don't, we reserve the right to disable automatic opt-in from your instance.

  To enable the bridge for a web site, make a form-encoded HTTP POST to https://fed.brid.gy/web-site with the web site's home page URL in the body's url parameter, eg url=example.com, and confirm=true. The web site must either support microformats2 and webmentions, or serve an RSS or Atom feed discoverable from its home page. To disable, put the text #nobridge in the web site's profile metadata, then make an HTTP POST to https://fed.brid.gy/web/[domain]/update-profile, where [domain] is the web site's domain, eg snarfed.org.

• As a server admin, can I give my new users custom Bluesky domain handles automatically?

• Yes! For Bluesky custom domain handles, you need to redirect the URL path /.well-known/atproto-did to Bridgy Fed from every subdomain that you want to use as a handle. You also need to include two query parameters: protocol, which is ap for fediverse accounts or web for web sites, and id, which is the ActivityPub actor id or WebFinger address for fediverse accounts, or the domain for web sites.

  Say you run a fediverse instance at instance.com, and your users' actor ids follow the pattern https://instance.com/users/alice, and you want to give each of your users a subdomain as their Bluesky handle, eg alice.instance.com for @alice@instance.com. You'd redirect https://alice.instance.com/.well-known/atproto-did to https://fed.brid.gy/.well-known/atproto-did?protocol=ap&id=https://instance.com/users/alice, and so on for each of your users.

  Likewise, if you run a web hosting service at example.com, with subdomains for each of your users, you'd redirect https://bob.example.com/.well-known/atproto-did to https://fed.brid.gy/.well-known/atproto-did?protocol=web&id=bob.example.com, and so on.

  This can often be done with a bit of web server config alone, without needing to change your instance's or service's code. You'll probably also use a wildcard DNS record and SSL certificate instead of provisioning individual DNS records and certificates per subdomain.

  After you've set up the redirect, email us or ping us on GitHub and we'll turn on automatic handles for your instance.

  Note that this only applies going forward, ie it won't retroactively change your existing users' Bluesky handles. They can change their handles by logging in or sending a DM, like usual. They don't need to do steps 1 or 2, ie set up DNS or HTTPS, just step 3 to trigger the handle change.

• Can I give my users custom fediverse addresses automatically?

• Yes! If you run a web hosting service, the process is similar to Bluesky custom handles. Set up the webfinger redirects for a web site first, before bridging it, and Bridgy Fed will detect them and automatically use its domain as its fediverse address instead of web.brid.gy.

  We don't currently have a way to automatically set a custom fediverse address for bridged Bluesky accounts. If you'd like that, feel free to file a feature request!

• As a client developer, can I show my user notifications, including from unbridged users?

• Yes! In general, when bridged users from other networks reply to or mention your users, they'll get normal notifications, automatically.

  When unbridged users from other networks reply to or mention your users, we send a DM with details and a link for them to respond. This DM comes from the Bridgy Fed bot user for that network, eg from ap.brid.gy for the fediverse, bsky.brid.gy for Bluesky, etc.

  You can intercept and parse these DMs to convert them to native-looking notifications. You can also let your users reply, like, repost, or block the user.

  On the fediverse, the DM activity's Note will include an attachment for each interaction. Its url field will be the user-facing URL for the interaction on its native network. It will also contain these Bridgy Fed custom fields in the bf: namespace (https://fed.brid.gy/ns#):

  • bf:respond: HTTP GET; renders a user-facing Bridgy Fed page where the user can interact with the post
  • bf:reply: HTTP POST; submit with a content body parameter to reply directly
  • bf:like: HTTP POST; like the post
  • bf:repost: HTTP POST; repost/boost the post
  • bf:block: HTTP POST; block the post's author

  All POST endpoints require a valid JWT token, which is included as a token query parameter in the URL.

  Example attachment:

  {
    "type": "Link",
    "url": "https://example.com/123",
    "bf:respond": "https://fed.brid.gy/fa/alice.com/respond?obj_id=https://example.com/123&token=...",
    "bf:reply": "https://fed.brid.gy/fa/alice.com/respond/reply?obj_id=https://example.com/123&token=...",
    "bf:like": "https://fed.brid.gy/fa/alice.com/respond/like?obj_id=https://example.com/123&token=...",
    "bf:repost": "https://fed.brid.gy/fa/alice.com/respond/repost?obj_id=https://example.com/123&token=...",
    "bf:block": "https://fed.brid.gy/fa/alice.com/respond/block?obj_id=https://example.com/123&token=..."
  }




Background

• Who are you? Why did you make this?

• We're Anuj Ahooja and Ryan Barrett. We make up A New Social, the non-profit that builds and runs Bridgy Fed. We love the open social web, and we hope that Bridgy Fed can help liberate people from their platforms and enable the last network effect.

• How much does it cost? Can I donate or support you?

• Bridgy Fed is entirely free to use, but it's not cheap to run, so we welcome donations on Patreon!

  If you can't afford to donate, but you still want to contribute, feel free to file an issue, send a pull request, or tell your friends to try it.

• What do you do with my data?

• Nothing! Bridgy Fed isn't a business, and never will be, so we don't have the same motivations to abuse your data that other services might. More concretely, we don't sell or otherwise expose any of your data to third parties, even in aggregate. We only handle data that you've chosen to make fully public.

• How long has this been around?

• Ryan started thinking about bridging different social networks when he discovered them in the early 2000s. He started talking about bridging decentralized social networks specifically in 2016, led a session on it at IndieWeb Summit in July 2017, wrote up concrete designs soon after, started working on Bridgy Fed in August 2017, and launched it on October 22, 2017.

• What are the terms of service?

• Bridgy Fed is both a service and an open source project. The open source code is placed into the public domain, via the CC0 license, and may be used by anyone for any purpose. The rest of these terms apply to the service.

  The Bridgy Fed service, served on *.brid.gy, is freely available to individuals and organizations to use for their own accounts.

  If you have a free, non-commercial product or hosting platform, you're welcome to integrate the Bridgy Fed service into it directly. Please let us know, we'd love to hear about your project!

  If you'd like to integrate the Bridgy Fed service into a commercial or paid product or service, that's great too! Please contact us, we can help. We'll probably also ask for, and expect, a reasonable donation.

  You agree not to deliberately attack, breach, or otherwise harm the service. If you manage to access private keys or other sensitive data, you agree to report the vulnerability and not use or disclose that data.

  Otherwise, you may use the service for any purpose you see fit. However, we may terminate or block your access for any reason, or no reason at all. (We've never done this, and we expect we never will. Just playing it safe.)

  Do you an administer an instance or other service that Bridgy Fed interacts with? If you have any concerns or questions, feel free to file an issue!

• What is your content moderation policy?

• Content moderation for decentralized social networks, and for bridges, is complicated. Bridgy Fed itself doesn't have an exhaustive content moderation policy. Instead, we try to follow these principles:

  • Our primary goal is to empower each network's existing moderation ecosystem. Most decentralized social networks have existing, often mature mechanisms for content moderation. The fediverse has blocks and defederation and IFTAS, the IndieWeb has Vouch and Akismet, Bluesky has labeling, even Nostr has mutes and shared mutelists and moderated groups.

    We try to ensure that those mechanisms all work with bridged accounts just as well as with native accounts, up to and including defederation. We're always ready to hear admins' concerns and try to help! But if an instance determines that they need to block a Bridgy Fed network (domain) entirely, that's their prerogative, and we support them.

  • Bridgy Fed is more network infrastructure than content platform. Bridgy Fed is not a social network, nor is it an instance in one. It's a relay: it copies and translates content and interactions between existing networks and platforms. It stores some content for a moderate period of time, in order to do its job, but not forever, and it doesn't host images or media at all.

  • Our team is tiny. Two people total, one primary developer, almost entirely self-funded. It's open source, and other people contribute occasionally, which is great! But so far it's just the two of us, sometimes full time, sometimes alongside other day jobs. We can't hire a trust and safety team, we don't plan to recruit volunteer moderators, and we're unlikely to become experts ourselves. We're just amateurs, with the support of organizations like IFTAS.

  • Regardless, we don't plan to run a Nazi bar. We have no interest in enabling harmful behavior like harassment or incitements to violence, whether knowingly or unknowingly. We reserve the right to remove content and accounts from Bridgy Fed for any reason, or no reason at all.

  These are principles, not a policy. The language here will evolve over time. This isn't a workflow that we follow letter by letter. Still, we hope to live up to this in spirit for the long run.

  Please reach out and let us know your thoughts! You can file an issue on GitHub, email us, or ping us on your social network of choice.

• I found a bug! I have a feature request!

• Great! Please file it in GitHub. Thank you!

• I found a security vulnerability!

• Oof. Thank you for reporting it! Please file an advisory on GitHub, subject to these rules:

  • Vulnerabilities must be in the application itself, not unrelated services like email (eg SPF/DKIM/DMARC).
  • Public user data is intentionally public. That's not a vulnerability.
  • No automated fuzzing, DoSes, or other high volume traffic. We block this traffic, and it will disqualify you from any possible award.

  Otherwise, the code is open source, feel free to try to break in, let us know if you succeed!

• What's your succession plan if you can't run Bridgy Fed any more?

• The succession plan for Bridgy Fed is largely the same as for any other non-commercial open source project. Ideally, we find someone willing to take it over, transfer the hosting and development accounts to them, and it continues running as is. Worst case, the code is open source and licensed as public domain, so anyone can set up their own instance and continue development. If that happens, bridged accounts based on on *.brid.gy subdomains and existing private keys would be orphaned, but the new instance could continue to bridge them with its new domain(s) and keys.




Development

• What are Bridgy Fed's product and engineering values?

• What's important to Bridgy Fed and its development? How do we make technical and design decisions and prioritize work? One way to do this is to explicitly enumerate its product and engineering values, along with their priorities. Bryan Cantrill describes this well.

  Bridgy Fed's top product and engineering values are:

  • Quality: expected functionality works consistently, with minimal bugs, surprises, or outages.
  • Functionality: common features and use cases are supported as broadly and comprehensively as possible.
  • Safety and security: Bridgy Fed minimizes harm to its users. The primary way this currently manifests is that it only bridges fully public data, and it enables and supports the networks' own moderation features (blocking, reporting, etc). It also uses modern secure coding and ops practices to minimize vulnerabilities that could expose private keys or other sensitive information.

  Bridgy Fed's second tier of product and engineering values are:

  • Accessibility: users should mostly fall into a "pit of success" with minimal work on their end. Discovering and following users on other networks should be as easy as possible. After that, all interactions should work automatically, transparently.
  • Transparency: it should be easy for users to understand what Bridgy Fed is doing. This includes per-user dashboard pages in the web UI, verbose public logs, and comprehensive documentation.
  • Scalability: we want to handle as much usage as we receive, as automatically as possible. This doesn't mean that Bridgy Fed is designed to handle millions of users today, just that it could be, and that we'd prioritize it.

Other possible values include maintainability, operability, feature velocity, innovation, debuggability, performance, efficiency, standards compliance, user growth, and more. Those can all be good, and we may aim at some of them too, but less than the explicitly chosen values above.

• How do the different protocols compare?

• Here's a table showing how they stack up on a number of factors. It's obviously oversimplified, but hopefully still right in spirit, focusing on how they're deployed and used in the real world. For example, identity in ActivityPub is technically URL-based, but in practice the fediverse uses WebFinger user@domain identifiers more or less universally, so the table reflects that.

  Feedback is welcome!

  	IndieWeb	ActivityPub + WebFinger	AT Protocol	Nostr	Farcaster
  governance	non-profit, W3C	W3C, FEPs	PBC now, IETF eventually?	BDFL, NIPs, adoption based	FIPs, adoption based
  user identity	DNS	username + DNS	did:plc + did:web, DNS handles	public key, DNS handles	public key, blockchain, ENS usernames
  object ids	URL	URL	at:// URI, data hash	data hash	user id + data hash
  data format	microformats2	ActivityStreams 2	app.bsky lexicons	Nostr events	Custom schema
  serialization	HTML	JSON	JSON (Lexicon), DAG-CBOR, CAR	JSON	Protocol Buffers
  delivery	push/pull posts, push responses	push	pull	pull	gossip + pull
  transport	HTTP	HTTP	HTTP + WebSocket (XRPC)	WebSocket	gRPC + libp2p
  topology	peer to peer	federated servers, two tier	federated servers, decoupled services, multi-tier	interchangeable relays, two tier	interchangeable hubs, two tier
  security model	SSL, one user per domain	transport signatures, custodial keys	data signatures, custodial + user-owned keys	data signatures, user-owned keys	data signatures, user-owned keys
  app semantics live in...	servers, clients	servers, clients	dedicated service, clients	clients	servers (hubs)
  blockchain	no	no	no	no	yes
  monetization	hosting	donations	services	microtransactions	signup, storage, microtransactions
  user base estimates (as of Oct 2024)	not well defined	1M MAU, 11M-15M total	4.8M MAU, 1.2M DAU, 10.8M total	32k WAU, 15k DAU, 190k total	167k MAU, 50k DAU, 690k total, but probably much less
  server estimates (as of Oct 2024)	not well defined	21k-30k	~300 PDSes, 5+ AppViews, ? relays	800-2800	19k

• How are the different protocols translated?

• Here are internal details on how Bridgy Fed translates user identity and events between protocols, including some like Nostr/AT Protocol that aren't launched here, or even fully implemented or thought through yet. Caveat hacker!

  In the tables below, BF is Bridgy Fed. Green parts have been implemented and running here for years, the rest are still in the early design phase.

  Here's how we translate user identity between protocols. Specifically, each cell shows how a user in a given column is identified to the protocol in a given row. These identities uniquely identify users, and are intended primarily to be machine readable and usable. (Scroll down for the equivalent table for translating human-meaningful user handles.)

  Note that Bridgy Fed generates some of these ids itself behind the scenes, notably AT Protocol did:plcs, Nostr npub public keys, and Farcaster fids.

  	Web domain	ActivityPub	AT Protocol	Nostr	Farcaster
  Web URL	-	AP actor id	https://bsky.brid.gy/web/[did]	NIP-05 domain or https://nostr.brid.gy/web/[npub]	https://fc.brid.gy/web/[fid]
  ActivityPub actor	https://web.brid.gy/ap/[domain]	-	https://bsky.brid.gy/ap/[did]	https://nostr.brid.gy/ap/[npub]	https://fc.brid.gy/ap/[fid]
  AT Protocol	did:plc	did:plc	-	did:plc	did:plc
  Nostr	npub	npub	npub	-	npub
  Farcaster	fid	fid	fid	fid	-

  Here's how we translate user handles (aka usernames) between protocols. Each cell shows how a user's handle in a given column is translated to the protocol in a given row. These handles are human-chosen, human-meaningful, generally unique, but may not be the primary machine-usable ids in each protocol. Scroll down to the next table for examples, up to the previous table for machine-usable ids.

  Basic is the default, enhanced requires extra setup on the user's part (or their fediverse instance's) to forward some of their /.well-known HTTP requests to Bridgy Fed.

  		Web	WebFinger	AT Protocol	Nostr	Farcaster
  Web		-	Fediverse profile URL	bare handle	NIP-05 domain	[username] (fully qualified)
  WebFinger	basic	@[domain]@web.brid.gy	-	@[handle]@bsky.brid.gy	@[NIP-05 or npub]@nostr.brid.gy	@[username]@fc.brid.gy
  	enhanced	@[domain]@[domain]		@[handle]@[handle]	@[NIP-05]@[NIP-05]	?
  ATP handle	basic	[domain].web.brid.gy	[username].[instance].ap.brid.gy	-	[NIP-05 or npub].nostr.brid.gy (convert @ in NIP-05 to .)	[username].fc.brid.gy
  	enhanced	bare domain	bare domain		bare NIP-05 domain (_ username)	?
  Nostr NIP-05 domain	basic	[domain]@web.brid.gy	[username].[instance]@ap.brid.gy	[handle]@bsky.brid.gy	-	[username]@fc.brid.gy
  	enhanced	bare domain	[username]@[instance]	bare handle		?
  Farcaster	basic	[domain].fcast.id	[username].[instance].fcast.id	[handle].fcast.id	[NIP-05 or npub].fcast.id	-
  	enhanced	[domain.eth]	[domain.eth]	[domain.eth]	[domain.eth]

  Here are concrete examples:

  		Web me.com	ActivityPub @me@instance.com	AT Protocol me.com	Nostr me@domain.com [_@]me.com	Farcaster me.fcast.id me.eth
  Web		-	https://instance.com/@me (varies by instance)	me.com	? me.com	me.fcast.id me.eth
  ActivityPub	basic	@me.com@web.brid.gy	-	@me.com@bsky.brid.gy	@me.[domain.]com@nostr.brid.gy	@me@fc.brid.gy @me.eth@fc.brid.gy
  	enhanced	@me.com@me.com		@me.com@me.com	@me@domain.com @me.com@me.com	?
  AT Protocol	basic	me.com.web.brid.gy	me.instance.com.ap.brid.gy	-	me.[domain.]com.nostr.brid.gy	me.fc.brid.gy me.eth.fc.brid.gy
  	enhanced	me.com	me.com		me.[domain.]com	?
  Nostr	basic	me.com@web.brid.gy	me.instance.com@ap.brid.gy	me.com@bsky.brid.gy	-	me@fc.brid.gy me.eth@fc.brid.gy
  	enhanced	[_@]me.com	[_@]me.instance.com	[_@]me.com		?
  Farcaster		me.com	me.instance.com	me.com	me.[domain.]com	-

  Here's how we infer the protocol for any string id. In the Format column, green parts are deterministic, ie they conclusively determine that a matching id belongs to the protocol, and yellow parts are ambiguous, ie a matching id may or may not belong to the protocol:

  		Example(s)	Format	Network discovery
  Web	user	snarfed.org https://snarfed.org/	domain, http(s) URL with empty path	HTTP GET succeeds and returns HTML
  	object	https://snarfed.org/2023-05-26_50328	http(s) URL with non-empty path
  ActivityPub	user	https://indieweb.social/users/snarfed	http(s) URL	HTTP GET with AS2 conneg returns valid AS2 with Actor type
  	object	https://mitra.social/post/01885fad		HTTP GET with AS2 conneg returns valid AS2 with non-Actor type
  AT Protocol	user	did:plc:abc123 did:web:snarfed.org	did:plc or did:web	resolve did:plc, resolve did:web
  	object	at://did:plc:asdf/post/abc-123	at:// URI	com.atproto.repo.getRecord XRPC
  Nostr	user	nostr:... abc123... npub10hx886...	NIP-21 URI 32 char hex npub or nprofile NIP-19	NIP-65 lookup + REQ request
  	object	nostr:... def456... nevent10hx886...	NIP-21 URI 32 char hex nevent or note NIP-19	REQ request
  Farcaster	user	12433 farcaster://12433	uint64 fid farcaster: URI	GetUserDataByFid gRPC to hub
  	object	- farcaster://12433/0x123abc...	20-byte BLAKE3 hash farcaster: URI	GetCast, GetReaction, etc gRPCs to hub

  Here's how we translate events and operations between protocols, both inbound to and outbound from Bridgy Fed:

  	Web	ActivityPub	AT Protocol	Nostr
  User discovery inbound	serve h-card on BF user page	basic: serve WebFinger and AP actor on fed.brid.gy enhanced: user's site serves and redirects WebFinger to fed.brid.gy	resolve DID, serve DID document with fed.brid.gy PDS	NIP-39 (kind 0) query to BF (or other?) relay
  User discovery outbound	Fetch home page, parse h-card	look up WebFinger, fetch AP actor	resolve DID, subscribe to PDS repo, extract profile object?	discover user's relays with NIP-65, query NIP-39 to get profile
  Publish inbound	webmention to fed.brid.gy	deliver to fed.brid.gy inbox, user or shared	receive post via firehose from relay	publish event to BF relay
  Publish outbound	serve on BF user page followings h-feed	deliver to recipient's inbox	serve commit via subscribeRepos XRPCs to subscribing relays	serve to subscribers
  Follow inbound	users: UI on BF user page code: webmention with u-follow-of	Follow activity delivered to BF user inbox	receive follow via firehose from relay	user's client sends REQ to BF relay
  Follow outbound	webmention with BF proxy HTML page as source	deliver Follow to followee's inbox	call sync.subscribeRepos on followee's PDS?	discover followee's relay(s) with NIP-65, send them a REQ
  Response inbound	webmention to a BF proxy page	Create, Like, Announce delivered to BF user inbox	receive response via firehose from relay	NIP-10 response event received at BF relay or other relay
  Response outbound	same as follow outbound, with the corresponding response data type

• How are activities routed?

• A bridge does more than just translate protocols and formats. It processes activities (events) based on domain-specific logic and semantics. The domain Bridgy Fed currently handles is public social microblogging, the kind popularized by Twitter. There are many other related social domains, with fuzzy boundaries and lots of overlap, eg forums (Reddit), questions and answers (StackOverflow), project trackers (GitHub), and many more, but here we're currently focused on microblogging.

  Even within that domain, behavior logic varies. Twitter follows are one way, but Facebook friends are bidirectional. Your Bluesky timeline (skyline) includes your followings' replies, but your fediverse timeline generally doesn't. LinkedIn...honestly I have no clue how LinkedIn works, but I'm sure it has its own logic, workfluencers and all.

  Here's what Bridgy Fed's activity router does. I've tried to make it follow "least common denominator" logic, ie do the most common and least surprising thing, and I've explicitly tried not to innovate or invent anything new here. It's a bridge, not a product, after all.

  When Bridgy Fed receives a...	The router will...
  follow	deliver the follow activity to the followee automatically send an accept activity to the follower (we may eventually add UX for this) store the follower locally generate a local notification to the follower
  unfollow	deliver the unfollow activity to the followee deactivate the locally stored follower
  new post	deliver to all active stored followers store the post locally
  update post	deliver to all active stored followers update the locally stored post
  delete post	deliver to all active stored followers mark the locally stored post deleted
  delete actor	deactivate their locally stored follows, to and from
  reply	deliver to the original post store locally generate a local notification to the original post's author
  repost	deliver to all active stored followers store locally generate a local notification to the original post's author
  like	deliver to the original post generate a local notification to the original post's author