Its features include
- HTML/CSS inspector on the type of Firebug, which allows easily to correlate the selected elements of page with a code and proper style.
- Context help on all supported languages. By pressing F1 key the page with detailed description for current tag, attribute or function will be opened.
- PHP debugger allows to execute PHP scripts incrementally, watching the values of all variables in every line.
- SQL manager allows to produce all necessary actions with a database - to add, delete, edit a structure and records in tables, to export data, execute SQL queries. Highlighting and autocompletion works for SQL files also.
- Support of FTP allows to work straight with a remote server and to do all necessary changes with files.
- The portable option allows to use editor without the preliminary installation.
- Other useful utilities: pair highlighting, possibility of blocks selection, collapsing, tooltips, navigation on descriptions of functions and included files at withholding of the key of CTRL, viewing of structure of files and project, preview in a browser, book-marks, and all other standard possibilities for work with a code.
- Plugins available for Drupal, Joomla, CakePHP, CodeIgniter, Symfony, Yii, JQuery, WordPress, Smarty
It is NOT open source. It has Free, Lite and Professional editions available. Free editon has limited set of features but it is worth to take a look.