Jenkins
Open Source
Jenkins is a self-contained Java-based program, ready to run out-of-the-box, with packages for Windows, Mac OS X and other Unix-like operating systems.
Buildkite
Commercial
Buildkite is a CI and build automation tool that combines the power of your own build infrastructure with the convenience of a managed, centralized web UI.
Compare Semaphore with alternatives
Compare Buildkite and Semaphore and decide which is most suitable for you.