Jenkins

Jenkins REST API provides comprehensive CI/CD automation with REST-like endpoints available under .../api/ URLs for each resource.

Authentication uses HTTP Basic Auth with username and API token (recommended over passwords since v1.426).

The API covers jobs, builds, views, nodes, plugins, and queue management extensively. Each Jenkins page includes an API link showing available endpoints for that resource. Client libraries available for Java (jenkins-rest), Python (jenkinsapi, python-jenkins), Ruby (jenkins_api_client), and Node.js. Supports JSON and XML output formats with XPath filtering and depth control for nested data. CSRF protection requires crumb tokens for POST requests.

No formal OpenAPI spec exists, though community projects like swaggy-jenkins provide partial documentation. It's ideal for build automation, custom dashboards, and DevOps integrations, though the lack of centralized documentation can be challenging for newcomers.