The Aptana Studio based on the Eclipse IDE, is a usefully ide for develop the complex web application(e.g. AJAX, B/S Programs). I very like the code completion and the cross browser compatible detection features.
The Aptana is cross-platform, free, and open-source. Provided are differents installation type both standalone and Eclipse plugin, You can download the Aptana plugin to improve your existing Eclipse IDE or new standalone IDE.
Unified Editing for Web Apps
Get unrivaled support for popular libraries including jQuery, Prototype, YUI, dojo, Ext JS, MooTools, and others.
Ruby on Rails, Python and PHP
Use your skills to create desktop web applications with our plugin for Adobe AIR.
Free, Open Source and Cross Platform
Download Aptana Studio for Windows, Mac, or Linux. Both the standalone and Eclipse plugin distributions are free, open source software.
Yeah, it’s in there.
Quoted from Aptana homepage