Woodpecker CI

GitHub Actions

actions/runner

Popular

CI/CD built into GitHub with a huge marketplace of reusable actions; the most used CI in open source.

GitLab CI/CD

docs.gitlab.com

Popular

Pipelines built into GitLab's DevSecOps platform, with self-managed runners and built-in security scans.

Jenkins

jenkinsci/jenkins

Popular

Self-hosted automation server with 2,000+ plugins; still widespread in enterprises despite its age.

Azure Pipelines

azure.microsoft.com

Azure DevOps CI/CD with YAML pipelines, hosted agents and deep Microsoft ecosystem integration.

CircleCI

circleci.com

Hosted CI/CD with fast caching, parallelism and reusable orbs; a long-time choice for SaaS teams.

Bitbucket Pipelines

atlassian.com

CI/CD built into Atlassian Bitbucket Cloud, configured with a bitbucket-pipelines.yml file.

Buildkite

buildkite/agent

Hybrid CI with hosted orchestration and self-hosted agents; favored by large monorepo engineering orgs.

TeamCity

jetbrains.com

JetBrains CI/CD server popular with .NET, Java and game-development teams.

Tekton

tektoncd/pipeline

Kubernetes-native CI/CD building blocks (Tasks, Pipelines) as CRDs; the base of OpenShift Pipelines.