Jenkins CI is the leading open-source continuous integration server. Built with Java, it provides over 400 plugins to support building and testing virtually any project.
Pro Users can source control their chain of automation
Starting with Jenkins 2.0, the pipeline capability, which has been available as a plugin before this version, has been built into Jenkins itself. This allows developers to describe their chain of automation in text form, which can be version controlled and put alongside the source tree.
Pro Stable release line for users who want less changes
This is called the Jenkins Long-Term Support (LTS) version and helps to provide the most stable and assuring version of the Jenkins CI possible. Every 3 months, a version (which has been deemed the most reliable by the community) is chosen. After this, its branched, well-tested features are added (if they are missing), it is tested with the new features, bug fixes are then carried out if necessary, and from there it is released as the official Jenkins LTS version.
Con Unstable and lack of plugin integration QA process
Jenkins without plugins is almost useless. All plugins are treated equal and published almost right away.
Because there is no process for testing Jenkins' integration, the overall Jenkins experience is not that great. Furthermore, Jenkins' core and plugins are released on a regular basis, all requiring instant restarts, meaning that updates appear more than once a day!
Con Poor quality plug-ins that are difficult to combine
There have been several complaints by users regarding the quality of the plug-ins found in Jenkins' official plugin repo. A lot of plugins found in the default plugin directory are no longer actively maintained and as a result, they may be incompatible with later versions of Jenkins or other plugins.