PHPStan finds bugs in your code without writing tests. It's open-source and free. PHPStan scans your whole codebase and looks for both obvious & tricky bugs. Even in those rarely executed if statements that certainly aren't covered by tests. You can run it on your machine and in CI to prevent those bugs ever reaching your customers in production. Thanks to rule levels you don't get overwhelmed with thousands of errors on the first run. You can increase PHPStan's capabilities on your code at...
Free Static Code Analysis Tool for PHP Applications
RIPS is a static code analysis tool for the automated detection of security vulnerabilities in PHP applications. It was released 2010 during the Month of PHP Security (www.php-security.org).
NOTE: RIPS 0.5 development is abandoned. A complete rewrite with OOP support and higher precision is available at https://www.ripstech.com/next-generation/