One more tool for the standard toolkit: JODE Eclipse Plugin. By adding this plugin (and making one small configuration change), you will no longer see the "No source attachment" page when you navigate to a class provided by a JAR. Instead, it uses JODE to decompile the class back to source code and shows you that. It does a quite credible job, especially if the class was compiled with debugging symbols. This is usually more than sufficient for when I have a simple question about an API ... better than hunting around for the source on the web, or finding a source download to attach.