Aptana Studio Community Edition

Aptana Studio is a powerful, free and open source Ajax development environment which runs stand-alone or within Eclipse. Aptana Studio offers unparalleled tooling for Ajax including HTML, CSS, DOM, and JavaScript editing and debugging, plus support via additional free plugins for PHP, Ruby on Rails, Adobe AIR, Apple iPhone development.

Aptana Studio’s integrated code assist, documentation and API reference not only eases working with popular Ajax libraries like prototype, scriptaculous, dojo, jQuery, ExtJS, MooTools, and others, it also works for the core scripting languages and your own code.