Dontbug is a reverse debugger (aka time travel debugger) for PHP. It allows you to record the execution of PHP scripts (in command line mode or in the browser) and replay the same execution back in a PHP IDE debugger. During replay you may debug normally (forward mode debugging) or in reverse, which allows you to step over/out backwards, step backwards, run backwards, run to cursor backwards, set breakpoints in the past and so forth. Debugging with the ability to run in reverse allows you to hunt down bugs much more easily. It also allows you to understand the runtime behavior of large PHP codebases more efficiently.