Please see the CI/CD box at the top right of the Cloud Native Landscape: https://github.com/cncf/landscape#current-version

(Disclosure: I'm the author.)

Hosted: GitHub, SourceForge, BitBucket

Self-hosted: Gitea/Gogs, Phabricator, Tuleap

All the tools that have been mentioned already and Visual Studio Team Services, which offers agile project planning, unlimited private git repositories (free for up to 5 users) and hosted CI/CD pipelines. http://visualstudio.com/team-services

I'd say Github, Atlassian (Bitbucket server), RhodeCode, Perforce (after acquisition of Deveo)