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composer/composer

📈 Trending★ 29,414PHPAudience · developerComplexity · 2/5ActiveLicenseSetup · easy

TLDR

Dependency manager for PHP that automatically finds compatible versions of external libraries, downloads them, and sets up your project to use them.

Mindmap

mindmap
  root((Composer))
    What it does
      Manages dependencies
      Resolves versions
      Autoloads libraries
    How to use it
      Declare in config file
      Run install command
      Update packages
    Tech stack
      PHP 7.2.5+
      Git, unzip, tar
    Use cases
      Start new projects
      Add libraries
      Update versions
    Distribution
      Packagist.org public
      Private Packagist paid

Things people build with this

USE CASE 1

Start a new PHP web project by declaring dependencies in composer.json and automatically installing all required libraries.

USE CASE 2

Add a new third-party package to an existing project and let Composer resolve version conflicts with your current dependencies.

USE CASE 3

Update all your project's libraries to their latest compatible versions with a single command.

USE CASE 4

Share your PHP project with other developers who can install the exact same dependency versions you used.

Tech stack

PHPGitUnzipTar

Getting it running

Difficulty · easy Time to first run · 5min
Use freely for any purpose, including commercial use, as long as you keep the copyright notice and license text.

In plain English

Composer is a dependency manager for PHP, the programming language widely used for web applications. The problem it solves is coordinating which external code packages a project needs, finding compatible versions, and installing them automatically, rather than requiring developers to download and manage each piece manually. You declare the libraries your project depends on in a configuration file, and Composer figures out a set of versions that all work together, then downloads them. It also handles autoloading, meaning it sets up PHP so your code can find and use those libraries without extra configuration. Public packages are distributed through Packagist.org; private hosting is available through Private Packagist. The tool is written in PHP itself and requires PHP version 7.2.5 or higher for its latest release. An older long-term-support version supports PHP from 5.3.2 through 8.1. It optionally uses command-line tools such as git, unzip, and tar to handle different archive formats. Anyone writing a PHP project would use Composer. It is the standard way PHP developers manage external libraries, roughly analogous to npm for JavaScript or pip for Python. You would reach for it at the start of a project to pull in the packages you need, and again when updating those packages or adding new ones.

Copy-paste prompts

Prompt 1
How do I create a new PHP project with Composer and add the Laravel framework as a dependency?
Prompt 2
I have a composer.json file, what does 'composer install' do and how is it different from 'composer update'?
Prompt 3
Show me how to require a specific version of a package in Composer and lock it so teammates use the same version.
Prompt 4
How do I use Composer's autoloader in my PHP code to access classes from installed packages without manual includes?
Prompt 5
What's the difference between composer.json and composer.lock, and why should I commit both to version control?
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Generated 2026-05-18 · Model: sonnet-4-6 · Verify against the repo before relying on details.