Dead code detector is a PHPStan extension for finding unused PHP code across your entire codebase. It detects dead methods, constants, enum cases, and properties, including transitive dead code chains and dead cycles. It supports popular frameworks and libraries including Symfony, Laravel, Doctrine, Twig, PHPUnit, Behat, and Nette. Features include automatic removal of detected dead code, customizable usage providers via reflection-based or AST-based APIs, test-only usage exclusion, and detailed debugging output. Configuration is done via phpstan.neon and the tool auto-enables library support based on composer dependencies.