Apache NetBeans
A fast and lightweight IDE
Vampirio Code, a great Code Editor and Compiler
Complete PHPDocs, directly from the source
A web based file manager, web IDE / browser based code editor
Komodo Edit is a fast and free multi-language code editor
The professional, open source development tool for the open web
Light-weight Scintilla-based text editor with syntax highlighting
Browser based code editor, allowing you to code from anywhere
PHP Support for GNU Emacs
Cloud-based Integrated Development Enviroment
Developer's friendly IDE