StatsD is a front-end proxy for the Graphite/Carbon metrics server, originally written by Etsy’s Erik Kastner. It is based on ideas from Flickr and this post by Cal Henderson: Counting and Timing. The server was written in Node, though there have been implementations in other languages since then.
A network daemon that runs on the Node.js platform and listens for statistics, like counters and timers, sent over UDP or TCP and sends aggregates to one or more pluggable backend services (e.g., Graphite).
Etsy blog / Code As Craft
Monitis: Network & IT Systems Monitoring