Bitsocial and Urbit
Urbit is a network of personal servers. Each user has an always-on computer called a ship, which runs Urbit's own operating system (Arvo), written in its own languages (Nock and Hoon), and is identified by an Urbit ID. Its main social app is Tlon Messenger, built by Tlon, the company founded in 2013 to develop Urbit.
Urbit aims to replace the whole computing stack, so it is a far broader project than Bitsocial. Its social layer, though, uses a model close to Bitsocial's: a community lives on its owner's node, and that node decides what gets in. The two differ on who has to run a server and on how spam is kept out.
How Urbit works
- Urbit IDs. Every ship has an Urbit ID: a number shown as a pronounceable name such as
~sampel-palnet. Layer 1 IDs are NFTs whose ownership and networking public keys are recorded in the Azimuth contracts on Ethereum. Layer 2 IDs, added in 2021 to cut fees, use a "naive rollup": their transactions are posted to Ethereum in batches, but their ownership is not stored in the Azimuth contract, and each ship computes it locally. Tlon runs a roller that is free for public use, according to the Urbit ID docs and Get on Urbit. - A fixed hierarchy. The address space has 256 galaxies, 65,536 stars and about 4 billion planets for everyday use. Galaxies issue stars, stars issue planets, and each planet can issue moons for its own devices. Comets are free IDs that a ship generates for itself and that never touch the blockchain. Galaxy owners form the Galactic Senate, which votes on upgrades to the Azimuth contracts and elects the Urbit Foundation's board.
- Networking. Ships exchange encrypted packets peer to peer. Since July 2026 the network protocol has been Directed Messaging, a content-centric rewrite of the older Ames protocol. Galaxies handle peer discovery: each one keeps track of where the ships beneath it are, and relays packets to them until the two ships can reach each other directly, or for as long as a firewall prevents that, according to the Directed Messaging paper.
- Groups. In Tlon Messenger, a group is hosted by its creator's ship. Members send messages to the host, which distributes them to every member's ship, and each member's ship keeps its own copy, according to the Tlon FAQ. The host controls roles, channels and admission. A group can be public, private or secret, and it can ban individual ships or whole ranks of ID. Channels are chats, notebooks or collections of images and links.
- Hosting. Signing up with Tlon gives a new user a ship that Tlon runs, with keys that Tlon holds in custody. A user can export the ship and its master ticket and run it elsewhere: on a Native Planet device, or with the Vere runtime on Linux, macOS or Windows. Ships cannot yet store large files directly, so Tlon Messenger puts images and other media in S3-compatible cloud storage.
Where they differ
Who has to run a server
On Urbit, every participant is a server. Tlon's apps are front ends for the user's own ship, and even reading a group goes through it. People who do not run a ship themselves rent one, which brings a hosting provider back into the picture: Tlon holds hosted users' keys and keeps limited access for maintenance, although users can leave with their whole ship.
On Bitsocial, only community owners need an always-on node. Readers and posters can run a peer-to-peer node inside a browser tab, and their account is a keypair that the app keeps. See Browser Peer-to-Peer. When someone does use a hosted node, Bitsocial's design aims to let them delegate uptime without handing over custody of the identity. See Identity and Community Ownership.
The community host
This is where the two are closest. A Tlon group and a Bitsocial community both live on their owner's node. The host decides who may post, applies moderation and distributes the result, and neither protocol puts a moderator above the host. In both, the host has to be online. Tlon's FAQ says that if the host goes offline, "the group goes down with them", and a Bitsocial community cannot accept new posts while its node is offline.
They store content differently. Every member's ship keeps a copy of the group's history, so members can still read what they already received while the host is down. A Bitsocial reader fetches the community's latest state from the community's node or from peers that seed it, so an offline community stays readable while peers have it, but the network keeps only the latest state.
A Tlon group also has a member list, and its host can make it invite-only. A Bitsocial community has no membership: anyone can read it, and anyone can try to post, subject to its challenge.
Spam and identity
Urbit fights spam by making identity scarce. The supply of planets is fixed and every one is issued by a star. Free comets get around that scarcity, so groups that want it to hold turn them away: Urbit's docs note that some groups refuse comets, and a Tlon group can ban the whole comet rank with one setting. Once comets are shut out, a banned user needs another planet from a star's owner to come back. Reputation can also follow the hierarchy: Azimuth includes a Censures contract that lets galaxies and stars flag IDs. Because the scarcity is built into the address space, it works the same way in every group that turns comets away.
Bitsocial identities are free keypairs. Each community chooses its own challenge before accepting a post, such as a captcha, a payment, a token balance or an allowlist, and other communities can choose differently. See Custom Anti-Spam Challenges.
Blockchain and governance
Urbit's identity layer depends on Ethereum. The Azimuth contracts record Layer 1 ownership and networking keys, Layer 2 transactions are posted to Ethereum in batches, and the Galactic Senate can upgrade the contract that governs Azimuth. The same 256 galaxies also handle peer discovery and relaying, so a fixed set of identities carries both governance and part of the network's routing.
Bitsocial identities are keypairs that need no registration. .bso and .eth names are optional
aliases that resolve to them. Peer discovery goes through HTTP routers that only return provider
addresses; anyone can run one, and clients can switch routers by changing their configuration.
Scope
Urbit is a general-purpose computer. A ship can host a Git remote, a personal knowledge base or AI agents, and Tlon Messenger is one program among many. Building for Urbit mostly means writing Hoon apps for Arvo. Bitsocial is a protocol for public communities, with apps such as 5chan and Seedit. It runs on the existing stack (libp2p, IPFS and the browser) instead of replacing it, and its clients are built with ordinary web tooling. See Build Your Own Client.
Private messages
This is where Urbit is stronger. Direct messages go from one ship straight to another, all traffic between ships is encrypted, and groups can be private or secret. Tlon notes that messages are encrypted in transit but stored unencrypted on the ship. Bitsocial focuses on public communities and has no native direct messages yet.
Project status
Urbit has been through upheaval. In August 2024 the Urbit Foundation, the nonprofit that steers core development, fired its executive director; founder Curtis Yarvin returned to lead strategy without a formal title, several core developers left, and the Foundation's runway was measured in months, CoinDesk reported. Yarvin proposed moving Azimuth to an existing Ethereum layer 2, with Base the likely choice, and issuing fungible "visa" tokens that convert into planets. As of October 2026, Urbit's ID documentation still describes Azimuth on Ethereum with its naive rollup. In October 2025 the Galactic Senate replaced the Foundation's board, and the new board appointed a new executive director (announcement).
Development continues. Directed Messaging went live with the 408k release on July 14, 2026. In June 2026 Tlon Messenger opened public sign-ups without a waitlist, and Tlon now presents itself as a place where people and AI agents work together.
Comparison
| Question | Urbit | Bitsocial |
|---|---|---|
| Category | Personal-server network and operating system | Peer-to-peer community network |
| Identity | Urbit IDs: about 4 billion planets on Ethereum or its Layer 2 rollup, plus free comets | Ed25519 keypairs for users and communities |
| Who runs a server | Every user, on their own ship or a hosted one | Community owners; readers and posters can use a browser tab |
| Where posts live | The group host's ship and a copy on every member's ship | The community owner's node and the peers that read and seed it |
| Communities | Groups hosted by their creator's ship, with member lists | First-class objects whose node accepts or rejects posts |
| Spam control | Scarce IDs issued by stars; groups ban ships or whole ranks | Each community's challenge before a post is accepted |
| Moderation | The group host's roles and bans | Community owners moderate their community; apps choose what they show |
| Peer discovery | Galaxies track and relay for the ships beneath them | HTTP routers return provider peers and store no content |
| Governance | The Galactic Senate of 256 galaxies votes on Azimuth upgrades | No protocol-level authority over identities or communities |
| Private messages | Encrypted direct messages and invite-only groups | Public communities; no native direct messages yet |
| Main tradeoff | A whole personal computer with private groups, but every user needs an always-on ship | Free identities and browser access, but no private messaging and only the latest state is kept |