There's a handy feature in the Symfony framework that provides a "debug bar" with information about the execution of your application. But what if you don't use Symfony for your development? Enter PHP DebugBar. This handy tool is easily installable via Composer and has lots of useful features including:

• Output of messages to the (Javascript-based) console
• Viewing exceptions
• Profiling database requests
• Showing an execution timeline
• Outputting the contents of the "request" (like superglobals)

It does all this completely independent of any other tool, so it's ready to drop into your application and go. You can find out more about the tool on the main project site or, if you'd like to contribute, you can find the project on Github.