Single-node · In-memory · gRPC

Heads up: I ended up switching to NATS + PostgreSQL. If you need consumer groups, bare NATS won't help — you need JetStream, which requires persistence. tinybroker fills the gap when you want in-memory consumer groups with no persistence overhead. The code works and is free to use; just know why you're reaching for it.

tinybroker’s wildcard subscription model composes into three distinct delivery patterns depending on how you assign subscription_id and consumer_group across your replicas.

Broadcast (fan-out)

Every subscriber receives every matching message. No coordination required.

Consumer Groups (balanced)

Each message is delivered to exactly one member of a named group, round-robin.

Singleton (leader election)

One active consumer at a time per group. Standby members promote automatically on disconnect.