What version constraint format should I use?

Composer uses semver-style constraints. Common patterns: ^1.2 (compatible with 1.2.x), ~1.2.3 (patch-level compatibility), >=2.0 <3.0, or a specific version like 3.0.1. The caret (^) constraint is recommended for most packages.

What is PSR-4 autoloading?

PSR-4 maps a PHP namespace prefix to a filesystem directory. For example mapping "App\" to "src/" means Composer will look for class App\User in src/User.php. It is the modern standard for PHP autoloading.

What should the package name look like?

Composer package names follow the vendor/package convention using lowercase letters, digits, and hyphens, e.g. my-company/my-library. Both parts are required and must be lowercase.

What is the minimum-stability field?

It controls which development states of packages are allowed: stable (default), RC, beta, alpha, or dev. Leave it as stable unless you intentionally need pre-release packages.

Can I add dev-only dependencies?

Yes. Toggle the "Dev dependency" checkbox when adding a package to place it under require-dev instead of require. These packages are only installed in development environments.

Composer JSON Generator

Name: Composer JSON Generator
Availability: InStock
Author: Nham Vu

Fill in your package details, add dependencies, configure autoloading and scripts, then download a ready-to-use composer.json file.

Package Info

Package Name *

Description

Type

License

PHP Constraint

Minimum Stability

Dependencies

dev

Leave empty to generate without dependencies.

PSR-4 Autoload

Namespace Prefix

Source Directory

Dev Namespace (optional)

Dev Directory

Scripts

composer.json

{
  "name": "vendor/package-name",
  "description": "",
  "type": "project",
  "license": "MIT",
  "require": {
    "php": ">=8.1"
  }
}

Quick-start

After downloading, run composer install in the same directory to fetch dependencies and set up autoloading.

Copied!

Summary

Fill in your package details, add dependencies, configure autoloading and scripts, then download a ready-to-use composer.json file.

How it works

Enter your package name in vendor/package format (e.g. acme/my-app).
Set a description, license, and minimum PHP version.
Add dependencies by typing the package name and version constraint.
Configure a PSR-4 autoload namespace and source directory.
Add optional Composer scripts such as test or lint commands.
Click Generate — preview the JSON and copy or download the file.

Use cases

Bootstrap a new PHP library or application quickly.
Generate a correct composer.json template when starting a project from scratch.
Learn the proper structure of composer.json without reading full documentation.
Add or validate version constraints before editing a real project file.
Set up PSR-4 autoloading for a custom namespace in seconds.
Create reproducible project scaffolding for team onboarding.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu