The Couchbase C client library is the core library for several other libraries. It is an asynchronous, single-threaded SDK using callbacks for all operations. It is available on Windows, Linux, and Mac OS X.
Currently, the latest version is 2.4.5. This SDK should be used for all development against Couchbase Server versions from 2.5 to 3.x.
C developers can find instructions on building or obtaining the library at http://docs.couchbase.com/developer/c-2.4/download-install.html. Numerous binaries are available at this location.