LavinMQ, an open-source message broker written in Crystal
RabbitMQ alternative in Crystal that runs on a fraction of the hardware.

Rembus exposes simple node and rpc primitives (expose/rpc) over a tiny brokerable WebSocket transport, so you can spin up remote functions in minutes. The unusual bit is treating a local DuckDB/DuckLake datalake as a first-class part of the runtime, which makes lightweight local analytics painless; I'd still want to see guarantees (delivery semantics, auth, scaling/benchmarking) before trusting it beyond prototypes.
Backend and distributed systems developers, Julia/Python engineers building small-to-medium distributed applications or prototypes
RabbitMQ alternative in Crystal that runs on a fraction of the hardware.
io_uring implementation bypasses OS thread context switches for zero-copy disk I/O.
Job queue that eliminates Redis/RabbitMQ by storing state in a single JSON file with CAS.
Built-in crypto verification beats email's SPF/DKIM/DMARC patchwork.
Ray and Prefect alternative claiming single-codebase distribution without the boilerplate.
Kafka proxy solving real scaling pain (HOL blocking) Uber shipped, but niche audience.