Build on the Cinderous relay
The Cinderous anchor relays are open to third-party Nostr apps through app lanes: a separate part of the relay with its own storage and rules, reachable at /app/<your-app-id>. There is no sign-up, no API key and no payment.
What you can build
App lanes are designed for apps that need a small, fast, shared meeting point rather than a permanent archive:
- Lobbies and presence — who is online right now (ephemeral events, never stored).
- Signalling — invitations and WebRTC offers addressed to one player.
- Asynchronous shared worlds — action logs that many players append to.
- Published game data — decks, loadouts and world snapshots as addressable events.
How to use it
- Connect to
wss://cinder-relay.cinderous1.workers.dev/app/<your-app-id>. Pick an id once and keep it — see Choosing an app id. - Publish events as usual. No AUTH is needed to write.
- Subscribe with a tag filter such as
{"#t": ["my-game"]}or withauthors. Filters without any scope are rejected — see Subscriptions.
The Quick start puts these three steps into one working example.
What it is not
- Not a general-purpose relay for social clients. Global feeds such as
{"kinds":[1]}are rejected by design, and the root path/belongs to the Cinderous messenger itself. - Not long-term storage. Everything expires; apps that are not on the known-tenant list keep data for only 2 hours unless they refresh it. See Retention and storage.
- Not private by default. Anyone who can form your filter can read your lane's events. Encrypt content yourself if it matters.
- No SLA. The anchors run on a free tier shared with the Cinderous messenger.
Resources and help
If a connection is refused, the relay tells you why in a NOTICE and a close reason before closing — see Error messages. Design background lives in the resources page, and questions go to GitHub issues.