Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
Ninja Build - Ninja is a small build system with a focus on speed.
CircleCI - CircleCI gives web developers powerful Continuous Integration and Deployment with easy setup and maintenance.
Meson - Meson is an open source build system meant to be both extremely fast, and, even more importantly...
Travis CI - Focus on writing code. Let Travis CI take care of running your tests and deploying your apps.
SCons - SCons is an Open Source software construction tool—that is, a next-generation build tool.