The differences of the open social networks#

Some people keep praising one architecture over another whether it be Nostr, the Fediverse, or ATProto (Bluesky). Why can't there be an actual comparison of the three over aspects that matter?

Core Identity Model#

The Core Identity Model is how each protocol handles user accounts, how portable accounts are, and how much trust you place in third parties.

• Nostr: Trustless cryptographic identity
  • On Nostr your identity is not bound to a server, instead your identity is a key you hold. Usually your secret key is represented by a string starting with nsec (you also have a public key starting with npub). In some cases your key may be held by a server (like with divine.video's account system), but most clients simply ask you to save the secret key securely. This identity model makes your identity trustless; you don't have to rely on someone else for your identity to exist.
• ATProto: PDS-held identities; you trust the PDS host
  • While the AT Protocol is based on cryptography, the identity system is designed where a third-party server (the Personal Data Server where your account is hosted) holds the keys. For most people this will be a server run by Bluesky PBC, the corporate entity that maintains Bluesky. This means that you are beholden to Bluesky PBC's existence for your account to exist, and that Bluesky PBC can delete your account if you do something they don't like. You can choose to move to another PDS, but then you're beholden to whoever owns that PDS.
• The Fediverse: Server-based non-portable identities; you trust the server owner
  • On the Fediverse you can sign up at any server you want, running whatever software suits you. You can join the Mastodon official instances (mastodon.social, mastodon.online), the Misskey official instance (misskey.io), some random community instance, or your own server. However, the Fediverse does not guarantee portability, meaning if one server starts enacting policies you don't like it may be impossible to move your existence from one server to another.

Data Storage Model#

The Data Storage Model is how each protocol handles user data (such as posts and media).

• Nostr: Independent relays and storage servers
  • On Nostr your posts and other social content are represented by JSON blobs called events or notes, which your client signs with your key and sends to one or more relays. If you add media to your posts, your client uploads that data to one or more Blossom media servers, and leaves a link to the media in your post. If a relay or media server stops accepting your content, you can find others that will, or you can host your own. Also, if one relay or media server goes down or wipes your data, your data is already replicated so it's still accessible.
• ATProto: Personal Data Servers
  • On ATProto the Personal Data Server (PDS) is where your account and data live, and it can only live on one PDS at a time. Your posts and social content are represented as JSON blobs "records" in a "repository" that lives on your PDS. The PDS also stores "blobs" which represent arbitrary files (usually the media you attach to posts). If the PDS goes down or the owners delete your account, your data's already gone so you can't move it to another server.
• Fediverse: Individual Instances
  • On the Fediverse your account and data live on whatever instance you signed up with. There's no uniform data structure you can see because each server can have a different implementation of software, sometimes not even designed for microblogging. If the instance you joined goes down or deletes your account, there's also no recourse.

Versatility#

Versatility pertains to multi-purpose operation. Is there a vast ecosystem of services accessible with one account, or is there less versatility in the one account you have?

• Nostr
  • On Nostr, your one key gives you access to many different clients that can do their own things or even give you access to the same content in different ways. Some clients may prioritize a Twitter-like experience, some may prioritize long-form blogging, some provide many things in one place, and some offer their own unique feature. Each type of event is distinguished by its kind number.
• ATProto
  • An ATProto repository can store multiple types of records in folders called collections or lexicons. The lexicons are written in a reverse-domain notation, so app.bsky.* pertains to the main Bluesky Social service, site.standard.* pertains to Standard.site-based blogging apps, and other apps will have their own lexicons. If you want to learn more about how it works, see this blog post by Bluesky user @danabra.mov.
• The Fediverse
  • There is no versatility within one Fediverse account. Fediverse servers of multiple types can communicate with each other, but you can't sign into PeerTube with a Mastodon account to upload a video. If you want to publish videos on PeerTube you'll have to sign up at a PeerTube instance. If you want to interact with Lemmy communities, you'll need an account at a Lemmy instance.