Buck is a build system developed and used by Facebook. It encourages the creation of small, reusable modules consisting of code and resources, and supports a variety of languages on many platforms.
Buck is a super-fast build system that encourages the creation of small, reusable modules over a variety of platforms and languages.
It is used at Facebook to build the Facebook's main Android app, Messenger, and Instagram as well as internal infrastructure at Facebook. The Gerrit project also uses it.