The text explores the evolution and current state of open-source Continuous Integration (CI) tools, highlighting a transition from older systems like CruiseControl and Jenkins to more modern solutions such as GitLab, Tekton, and Harness CI. These contemporary tools are designed with container-native and Kubernetes-native capabilities, offering enhanced efficiency and scalability for CI processes. The piece emphasizes the importance of CI in automating builds and tests, which are triggered by events such as code check-ins, with the ultimate goal of producing a deployable artifact. The text also discusses the community support, flexibility, and challenges associated with these tools, noting that while Jenkins remains popular due to its extensive plugin ecosystem, it faces criticism for being outdated and cumbersome. In contrast, newer tools like Tekton and Harness CI provide standardized, declarative configurations and easy extensibility, appealing to both open-source projects and large enterprises. The article concludes by suggesting resources for those considering both open-source and paid CI tools, aiming to assist in decision-making for selecting the appropriate CI platform.