Here is a list of all documented files with brief descriptions:

apiattr.h
assert.h
auth.h	Credentials store for Couchbase
cntl-private.h
cntl.h	Command codes for libcouchbase
couchbase.h	Main header file for Couchbase
crypto.h	Field encryption
environment.h
error.h	Definition of all of the error codes used by libcouchbase
intro.h
iometrics.h
iops.h	Public I/O integration interface
ixmgmt.h
kvbuf.h	Low level structures used by commands for buffers
libev_io_opts.h	Libev integration with libcouchbase
libevent_io_opts.h	Libevent integration with libcouchbase
libuv_io_opts.h	Libuv integration with libcouchbase
logger.h
mainpage.h
metrics.h
pktfwd.h
sysdefs.h
tracing.h
utils.h	Various utility functions
vbucket.h	VBucket Mapping API
visibility.h
wsaerr.h