Top Sites>Find Bugs Without Writing Tests | PHPStan

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# PHPStan - PHP Static Analysis Tool

> PHPStan finds bugs in your code without writing tests. It's a static analysis tool for PHP.

## Documentation

- [Getting Started](https://phpstan.org/user-guide/getting-started): How to install and start using PHPStan
- [Command Line Usage](https://phpstan.org/user-guide/command-line-usage): CLI options and usage
- [Rule Levels](https://phpstan.org/user-guide/rule-levels): Understanding PHPStan's rule levels (0-9)
- [The Baseline](https://phpstan.org/user-guide/baseline): Managing existing errors with a baseline
- [Discovering Symbols](https://phpstan.org/user-guide/discovering-symbols): Autoloading and symbol discovery
- [Output Format](https://phpstan.org/user-guide/output-format): Error output formats and formatters
- [Ignoring Errors](https://phpstan.org/user-guide/ignoring-errors): How to ignore specific errors
- [Error Identifiers](https://phpstan.org/error-identifiers): Complete list of all error identifiers
- [Stub Files](https://phpstan.org/user-guide/stub-files): Using stub files for type information
- [Troubleshooting Types](https://phpstan.org/user-guide/troubleshooting-types): Debugging type inference issues
- [Result Cache](https://phpstan.org/user-guide/result-cache): How PHPStan's caching works
- [Extension Library](https://phpstan.org/user-guide/extension-library): Available extensions
- [Config Reference](https://phpstan.org/config-reference): Full configuration reference

## Writing PHP Code

- [PHPDoc Basics](https://phpstan.org/writing-php-code/phpdocs-basics): Writing PHPDocs for PHPStan
- [PHPDoc Types](https://phpstan.org/writing-php-code/phpdoc-types): Detailed type syntax reference
- [Narrowing Types](https://phpstan.org/writing-php-code/narrowing-types): Type narrowing and type guards
- [Solving Undefined Variables](https://phpstan.org/writing-php-code/solving-undefined-variables): Fixing undefined variable errors

## Developing Extensions

- [Extension Types](https://phpstan.org/developing-extensions/extension-types): How to extend PHPStan