Jenkins

Jenkins isn't exciting. It's also been running our CI/CD pipelines reliably for years without a single vendor lock-in concern. Jenkinsfile gives you pipeline-as-code, the plugin ecosystem covers every integration imaginable, and self-hosting means you control the infrastructure.

For complex pipelines — multi-stage builds, Docker-in-Docker testing, conditional deployments, approval gates — Jenkins provides the flexibility that managed CI/CD services constrain. GitHub Actions works well for simpler workflows, but Jenkins wins when the pipeline itself is a significant piece of engineering.