This is the Javadoc for Jenkins core. Javadoc is available for the latest weekly release and for recent LTS releases. See choosing a Jenkins baseline for guidance choosing the minimum Jenkins core version for a plugin.
Stapler Javadoc describes the framework used by Jenkins to route requests to the objects handling them. Learn more.
Components Javadoc describes Jenkins components and libraries (currently a partial list of components).
Plugins Javadoc describes the newest releases of all Jenkins plugins, if available.