Ask HN: What CI(s) do you use in your company and why?

Is there a workflow that you need that such CI supports? Is there anything it misses?

I'll start: We use a self-hosted Concourse (https://concourse-ci.org) instance running Darwin/Linux/Windows builds that use our code signing certificates, but we use Circle CI for our non-cross platform needs, given its much faster and more stable. There are also some leftover projects using Appveyor CI and Travis CI, but they are all migrating to either Circle CI or Concourse.