Guide · updated 2026-10-05

How bitchat uses Nostr when the internet is up

Nostr is a simple protocol for signed notes passed through relays. bitchat uses it as the long-distance half of the app. The relays are not bitchat servers. They are a shared network that other software uses too.

Relays, not a headquarters

A relay accepts a signed message and hands it to other clients that asked for it. There are many relays. The Android project describes a large set of them rather than one account system. If a relay disappears, the protocol’s answer is another relay, not a ticket to a vendor. That is also the limit. A relay operator can refuse traffic, go offline, or log connection metadata such as IP addresses. “Decentralized” does not mean “nobody can see a connection”.

The app can reach this network through Tor, using Arti, which is the privacy option for the online path. Use it if you do not want your home address attached to a relay connection. It will be slower. It will not change what you typed into a public room.

What travels there

Geohash channels are the obvious Nostr feature. The room name is a map code, the messages are public to the room, and the keys used for that area are ephemeral in the design the project describes. People far apart can share a city room. People who never opened the mesh can share one too. Bluetooth is not involved.

The less obvious feature is the fallback for private messages. When two people have marked each other as favorites and the mesh cannot see both phones, the project says those direct messages can travel over Nostr instead. The thread keeps working on a normal network. It also stops being a purely local radio event. If you wanted the message to exist only on phones in one room, do not rely on a favorite fallback you have not checked.

What does not travel there

A local mesh conversation does not need a relay and should not be described as “on Nostr” just because the same app contains both. The routing is the point of the dual design. Offline, the packet hops. Online, and for geographic rooms, relays carry it. The feature page separates them so the install guide does not have to.

Cashu tokens that the app can preview are also not a Nostr essay and not a mesh essay. They are bearer notes. A relay, a screenshot, or a forwarded chat can be enough to lose the value. The release notes say as much. This guide repeats it because the button to preview a token sits inside the same app as the private mesh.

Why the APK page mentions Nostr at all

People download bitchat expecting a walkie-talkie and then find a globe. The globe is the Nostr half, drawn on the phone. Both halves ship in the same signed APK, universal or ARM64. You do not install a second app to get relays, and you do not uninstall Bluetooth to use them. You do need a network for that half, which is why an offline test of the app should be a test of the mesh channel.

The file to install is still the one on the download page, with the hash checked. Nostr does not make an unofficial repack safer. It gives a signed build somewhere else to talk.