Getting Started

Install

With a Rust toolchain:

$ cargo install efema-server

Or download the archive for your platform from the latest release - Linux on x86_64 and on 64-bit ARM (a Raspberry Pi), Windows and macOS on Apple silicon - and put efema-server somewhere on your PATH.

Run it

$ efema-server serve
2026-10-08T18:36:09.749999Z  INFO efema-server 0.1.0 listening on http://127.0.0.1:2451, data in /home/you/.local/share/efema

The relay listens on the loopback interface, port 2451, and keeps its data in your local data directory. Both have flags (serve):

$ efema-server serve --listen 127.0.0.1:8080 --data /var/lib/efema

Loopback is the default on purpose. The relay does not speak TLS and does not check who is asking yet - so before anything outside this machine reaches it, put it behind a reverse proxy and read the threat model.

Check it

$ curl http://127.0.0.1:2451/health
ok

Once devices have written to it, streams shows what the relay keeps - names, positions, epochs and sizes, never contents:

$ efema-server streams
STREAM  ID        EPOCH  ENTRIES       SIZE  UPDATED (UTC)
notes   11c3cd7e  1            3    1.7 KiB  2026-10-08 18:36
photos  6964d409  2            3  144.0 KiB  2026-10-08 18:36

What talks to it

Apps talk to it through the Rust client library, efema: it seals every entry on the device - there is no way to send one unsealed - keeps the device’s cursor and waits for news. Syncing an app shows how; A synced folder is a complete example to run against the relay you just started.

Anything else that speaks the protocol - CBOR over HTTP, four endpoints - is a client too, if it seals the way Sealing describes.

Next

• Streams and cursors - the model the relay keeps.
• Threat model - what the relay can see, and what it cannot.
• Syncing an app - the client library.
• Commands - the data directory, the logs and every flag.