CouchDB is an open source NoSQL document-oriented database. Couch is an acronym for Cluster Of Unreliable Commodity Hardware. It is largely written in Erlang, a concurrent, functional programming language.

CouchDB was developed by Damien Katz, who formerly worked on Domino 6 of the IBM Notes/Domino platform, and was first released in 2005 under GNU GPL. In 2008, it became part of the Apache project and hence been offered under Apache License.

In 2012, Damien left the CouchDB project for CouchBase Server, another multi-model NoSQL document-oriented database. He announced the move in his blog post The Future of CouchDB (January 4, 2012).