Psalm

Psalm is a popular static analysis tool tailored for PHP. It identifies potential issues in your code, including syntax errors, unused variables, and type mismatches, before you run the code. This helps to improve code quality and maintainability. It's quite powerful, it can even understand complex scenarios using its template/interface system. To analyze your PHP code with Psalm, you simply need to install it and then run it against your PHP file or directory.

Here's an example of how you might run Psalm against a file called 'example.php':

vendor/bin/psalm example.php