PHP Standards

PSR : PHP Standards Recommendation

PSR is a community-accepted standards that define how PHP code should be written and structured so that libraries and frameworks are interoperable and consistent.

They are published and maintained by the PHP-FIG (PHP Framework Interoperability Group).

In practice

Most modern PHP frameworks (Laravel, Symfony, Slim) follow PSR standards by default. If you follow PSRs, your code will integrate cleanly with third-party packages.

Most important PSR standards

Coding Style

PSR-1 – Basic coding standard (file structure, class naming, PHP tags)

PSR-12 – Extended coding style guide (indentation, braces, line length)

Autoloading

PSR-4 – Autoloading standard Maps namespaces to directory structures (used by Composer)

Interfaces & Architecture

PSR-3 – Logger interface

PSR-7 – HTTP message interfaces (Request/Response)

PSR-11 – Container (Dependency Injection)

PSR-15 – HTTP server request handlers (middleware)

PSR-18 – HTTP client interface