In PHP coding, we spend most of the time for debugging. Either we use echo, printr or vardump to check variable values or check whether a particular function is executing or not.
These all things are outputting something to browser. This is not applicable in case of redirection, or image processing (GD) or sometimes with callback url for Payment integrations.
header(Location: etc);may cause Warning : header is already sent , if you put an echo or debug and you cannot see the output, since it redirects into some other page.
Here is your remote debugging console to solve these problems. http://vardump.it
Copy the url from the site and use that url for your debugging purpose and keep the console open in another tab.
You can see these messages from your remote console http://vardump.it/253522 (last numbers are your unique key)
The debug url is formatted in this way: http://vardump.it/debug-id/your message here
Email me for more details.
More features like watch, break etc are under development