CircleCI

CircleCI builds a cloud and self-hosted CI/CD platform used by software engineering teams to automate builds, tests, and deployments from GitHub or Bitbucket. It sells subscription and usage‑based SaaS plans for teams and enterprises, with features for containers, parallelism, and security controls. Founded in 2011 and headquartered in San Francisco, the privately held company counts customers such as Hinge and Samsung.