Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
Travis CI - Focus on writing code. Let Travis CI take care of running your tests and deploying your apps.
Agola - A selfhosted open source CI/CD server build around the git workflow.
Buildbot - Python-based continuous integration testing framework
CircleCI - CircleCI gives web developers powerful Continuous Integration and Deployment with easy setup and maintenance.
Vexor.io - Vexor is a fast and cheap cloud continuous integration service with per-minute billing.