Composer is the de facto dependency manager for PHP, created by Nils Adermann and Jordi Boggiano. It introduced PHP to a npm/Cargo-style world where applications declare dependencies in composer.json, lock exact versions in composer.lock, and install reproducible trees from Packagist or private repositories.
Composer enabled the modern PHP renaissance — without it, neither Symfony components nor Laravel could be assembled the way they are today.
Dependency manager for PHP. Declare what you need, run install, get reproducible builds.
✨ Features
Default public registry. Hundreds of thousands of packages searchable and installable with one command.
composer.lock pins exact versions. CI installs the same tree every time, on every machine.
PSR-4 autoloading generated from package metadata. Class loaded on first use, no manual requires.
Hook commands into lifecycle events. Build custom plugins for installation behavior.
Satis and Private Packagist host paid or internal packages. Same workflow, your own catalog.
