Emacs Flymake PHPCS
Emacs Flymake PHPCS is a plugin for Emacs that hooks Emacs Flymake up to the PHP_CodeSniffer static analysis tool for PHP, providing you with on-the-fly feedback on code syntax, style and other warnings.
If you're familiar with the lint tools for various languages, this is what PHP_CodeSniffer provides.
You can find more on my GitHub page for Emacs Flymake PHPCS.
