Waf is a build automation tool designed to assist in the automatic compilation and installation of computer software. It is written in Python and maintained by Thomas Nagy.

Waf's source code is open source software, released under the terms of the New BSD License, though its accompanying documentation is under the CC-BY-NC-ND license, which forbids both modification and commercial redistribution: this prevents vendors such as the Debian project from including Waf documentation in their distributions.