How can I enable GZIP compression in Jetty?

You have to enable the GzipFilter to make Jetty return compressed content. Have a look here on how to do that: http://blog.max.berger.name/2010/01/jetty-7-gzip-filter.html

You can also use the gzip init parameter to make Jetty search for compressed content. That means if the file file.txt is requested, Jetty will watch for a file named file.txt.gz and returns that.