qrate - Node.js queue with concurrency and rate limiting

qrate is a Node.js queue library (v2.0.1, stable, low maintenance) that extends async.queue with configurable concurrency and rate limiting. It allows controlling the maximum number of workers running at any time and limiting the number of workers started per second. Key differentiators vs async: built-in rate limiting without external timers, and a drop-in replacement API. qrate uses an ESM-only module format, no TypeScript types shipped, and works in Node.js environments. It has no external dependencies.