Citrine

Citrine is a nostr relay that runs on Android, built by Greenart7c3. Every other nostr app on the same phone can connect to it over ws://localhost, read events from it, and write events to it. The app exposes a small UI to start and stop the relay, pick a port, set an icon, and manage which content resolvers are allowed to query it.

The point is to give a phone its own piece of nostr storage. Drafts and notes keep working when the device is offline, then get rebroadcast to public relays once it comes back online. Encrypted DMs, private lists, and other events the user does not want to push to a third-party relay can live on Citrine without ever leaving the device. Other clients on the phone can use it as a fast local cache to populate timelines without re-fetching the same events from the network on every launch.

The database can be exported and imported. An export can cover every event in the relay, or it can be limited to the events from a single account, which makes Citrine useful as a portable nostr backup.

Why fund it?

Most nostr clients still depend on a handful of large public relays for storage. That is fine for public posts, but every private DM, draft, or mute-list update that flows through those relays is a piece of data the user has handed to a third party. A local relay flips the default: the device keeps the canonical copy of the user's events, public relays are used to broadcast and discover, and the user can move between phones without losing history.

OpenSats announced long-term support for Greenart7c3 in October 2024, which funds his work on Citrine and its sibling project Amber.

What's next?

Recent work has focused on user experience improvements when Citrine is paired with Amethyst, background broadcast of events queued while the device was offline, and content-resolver integration so other apps on the same phone can query the relay without an extra setup step. Cross-platform support beyond Android is on the roadmap.