SQL Injection Cheat Sheet : Samples are provided to allow reader to get basic idea of a potential SQL Injection attack and almost every section includes a brief information about...
regex101 : Free PCRE-based regular expression debugger with real time explanation, error detection and highlighting.
schema.org : This site provides a collection of schemas that webmasters can use to markup HTML pages in ways recognized by major search providers, and that can als...
PHP Coding Standard Generator : The goal of this site is to enable you do very quickly create and maintain your own coding standard.
PHP Mess Detector rule sets files and PHP Code Sn...
The Joel Test : I've come up with my own, highly irresponsible, sloppy test to rate the quality of a software team : 12 Steps to Better Code.
This is a collection of known design patterns and some sample code how to implement them in PHP. Every pattern has a small list of examples (most of them from Zend Framework, Symfony2 or Doctrine2 as I'm most familiar with this software).