Kestrel vs. RSMQ vs. Sparrow

Kestrel is based on Blaine Cook's "starling" simple, distributed message queue, with added features and bulletproofing, as well as the scalability offered by actors and the JVM.

tl;dr: If you run a Redis server and currently use Amazon SQS or a similar message queue you might as well use this fast little replacement. Using a shared Redis server multiple Node.js processes can send / receive messages.

Sparrow keeps messages in memory, but persists them to disk, using Sqlite, when the queue is shutdown.