Buildbot - Python-based continuous integration testing framework
Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
Screwdriver - Yahoo's Continuous Delivery Build System for Dynamic Infrastructure
Bitbucket Pipelines - Bitbucket Pipelines brings continuous integration and delivery to Bitbucket cloud, empowering teams to build, test, and deploy their code.
Bamboo - Bamboo is a continuous integration and deployment tool that ties automated builds, tests and releases together in a single workflow.
Concourse - Pipeline-based CI system written in Go