Browser "development tools" are a great way to learn from others, but are they a security risk? I'm working on a project using PHP. My understanding is that PHP code is hidden. So, someone calling for "view source" would be looking at the results of the script, not the script. Much like CGI/Perl. That's great, but is it still hidden when someone uses the "developer tools"?
PHP is a back end programming language that is interpreted on the server side and outputs code that, eventually, gets served to the internet. The PHP code is never served unless you give the server permission to expose that code. Developer tools can only access code and data that you present to the internet.
So, no, developer tools do not expose anything you don't give it.