As of October 2, 2007, jo! is officially retired. In the past two years we unfortunately haven't been able to devote enough time to keep jo! up to date. Luckily there are great alternatives out there. Most notably jetty, Resin and Tomcat.

Thanks for having supported jo! We appreciate it.

jo! Small Screenshot - Click to enlarge!


jo! is a pure, free Java web server. It features:

  • HTTP/1.1 including byte-ranges, auto-chunking, pipelining, etc.
  • Servlet API 2.2 (2.3 starting with jo! 1.1)
  • JSP 1.1 (1.2 starting with jo! 1.1)
  • Source level JSP debugging a.k.a JSR-45 (starting with jo! 1.1)
  • Auto reload of WARs
  • Hot deployment of WARs
  • Drag and drop deployment of WARs
  • Auto internationalization
  • Auto servlet and jsp reloading
  • Easy to use Swing console
  • Advanced thread management
  • Memory sensitive file cache
  • Automatic compressed transfer of text or html files
  • Virtual hosts
  • Mac OS X support
  • Embeddable
  • ...

jo! is based on J2SE 1.4.x. It will not run under Java 1.3.x or less. Please take a look at the documentation (v1.1 docs) and history for further info.

Each release contains the full source code. However, if you want to contribute, please check out the latest sources from the cvs repository, which is hosted by SourceForge.

The latest release can be downloaded here.