PHP Standards Recommendations (PSR)

PSR stands for PHP Standards Recommendations. This is a set of rules and best practices, that may be adopted by any PHP project. It will help adopt common behavior and improve collaboration between projects.

PSR are edited by the PHP-FIG: Framework Interoperability Group.

There are 22 PSR in 2026, covering subjects such as cache, factories, log, coding standards, etc.

Documentation

See also PHP extension providing the accepted PSR interfaces, Why You Should Implement PHP Coding Standards (PSR) in Your Projects and The PSR Standards You Are Probably Ignoring.

Related : Framework Interoperability Group (FIG), Clock, Code Formatter, Dependency Injection Container, Interoperability, Middleware Pattern