Mostr Bridge Updates: Usernames, Hot Posts, and Encrypted DMs
Mostr, the Fediverse-Nostr bridge, now lets Nostr users reserve usernames, browse hot posts from across the bridge, and send encrypted DMs to Pleroma chats.
The Mostr bridge was the first thing Soapbox ever built for Nostr. To this day, it remains the top Nostr Relay by traffic, and the client with the largest userbase on Nostr: 54.2K active users. And this week it got three of its biggest updates yet.
The Fediverse is many times larger than Nostr, so connecting the two networks greatly increases the reach of Nostr content. It's a huge part of what makes Nostr the best place on the decentralized web: there's no server lock-in like on the Fediverse, but you can still talk to all your friends there. (For a deeper dive, see our comparison of Nostr, the Fediverse, and Bluesky.)
Every post flowing across the bridge is just ordinary Nostr data, which means you can browse and discover it from any client. The Mostr client page on Ditto is a great place to watch it all happen live:
Reserve Your Nostr Username on the Fediverse
The bridge has always worked in both directions, but naming was one-sided. Fediverse users arriving on Nostr automatically got handles like mk@spinster-xyz.mostr.pub. Nostr users heading the other way had no such luxury: you appeared on the Fediverse as your raw npub, a wall of random characters that nobody could read, remember, or mention in a reply. There was simply no way for your npub to not look like an npub over the bridge.
That's fixed. Nostr users can now register a NIP-05 name at mostr.pub, and it doubles as their ActivityPub handle. Register you and your account shows up as @you@mostr.pub on Mastodon and every other ActivityPub server, instead of the long npub username Fediverse users saw before.
Claiming a name isn't automatic, but we've already registered many popular Nostr accounts, so your name may be waiting for you.
A few things make this especially nice:
- Owned by your Nostr keys: no password, no account. You sign with the keys you already have.
- Works as a NIP-05 identifier: add
you@mostr.pubto your Nostr profile and show the verified checkmark in any client. - Renames move your followers: changing your name sends a Move activity to your Fediverse followers and keeps your old name reserved. You can rename once every 30 days.
Alex Gleason
July 18, 2026
On mostr.pub you can claim a username now. Then your Nostr account will show up as <username>@mostr.pub on Mastadon.
View post on Ditto →Hot Posts From Across the Bridge
The second update turns mostr.pub itself into a window onto the wider network. The homepage now shows hot posts from across the bridge: real posts from the Fediverse, appearing on Nostr right now, with a "New" tab when you want the raw firehose instead.
It's the fastest way to answer the question every newcomer asks: "so what actually crosses the bridge?" Answer: everything from butterfly photography to Bitcoin Core debates to the European Commission's textile policy. Each post links out to its Nostr copy and its Fediverse original, so you can explore whichever side of the bridge you prefer.
Encrypted DMs Now Bridge Between Nostr and Pleroma
The third update is private messaging. NIP-04 encrypted DMs (kind 4) now bridge to and from Pleroma ChatMessages, in both directions:
- A DM sent from any Nostr client to a bridged Fediverse user is decrypted and delivered to their Pleroma chats.
- A ChatMessage sent from Pleroma to a Nostr user arrives as an encrypted kind 4, readable in any Nostr client with DM support.
Privacy was the hard part. A kind 4 event's content is encrypted, but its metadata (who messaged whom, and when) is visible to any relay that stores it. Publishing DMs to ordinary public relays would expose that metadata to the world. So the bridge only publishes and reads kind 4 events on a small set of DM relays, relay.ditto.pub and relay.dreamith.to, which gate kind 4 behind NIP-42 AUTH. The bridge authenticates to those relays with its own dedicated key, and no DM metadata leaks to the public.
Only one-on-one conversations are bridged. Decryption works because the bridge controls the derived keys of bridged Fediverse users, the same mechanism it already uses to sign events on their behalf.
Alex Gleason
July 22, 2026
The Mostr bridge now bridges NIP-04 to Pleroma ChatMessage. It only works with relay.ditto.pub which requires AUTH so no metadata is leaked.
Under the Hood: Faster, More Reliable Bridging
Alongside the headline features, the bridge itself got sturdier. Profile events (kind 0) are now cached in Postgres, which dramatically cuts relay lookups for the most-requested data on the bridge. When a relay fetch does fail, actors are served from the database instead of erroring out. And the full NIP-05 user list no longer ships a bulky relays object, saving bandwidth on every resolution.
These changes build on this year's infrastructure work: the migration from SQLite to Postgres, and from Deno to Bun. Mostr has been running since 2023 and has processed hundreds of millions of requests. It just keeps getting better.
Reserve Your Username on Mostr Today
If you're on Nostr, your name is waiting. Good names are first-come, first-served, and the captcha only slows down the bots, not you.
Become @you@mostr.pub
Claim your name on the bridge and be a real person to 54.2K bridged users and the entire Fediverse.
Reserve your username on Mostr today!Frequently Asked Questions
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