Xdebug is an extension for PHP to assist with debugging and development by Derick Rethans.
- It contains a single step debugger to use with IDEs
- it upgrades PHP's
- it adds Stack traces for Notices, Warnings, Errors and Exceptions
- it features functionality for recording every function call and variable assignment to disk
- it contains a profiler
- it provides code coverage functionality for use with PHPUnit