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Packagist API

Free Packagist API with no key: PHP package metadata, all versions, dependencies, licences and autoload config from the Composer registry. Tested example.

No API key requiredHTTPSFree tier

Endpoint tested and returned HTTP 200 on 2026-08-19

What is the Packagist API?

The Packagist API is the free, key-free registry API for PHP Composer packages, providing package metadata, every published version with its dependencies, licences and autoload configuration.

Packagist is the default Composer repository, and its metadata is served from a static CDN endpoint designed for high volume. The `/p2/` path is the one to use — it is the same endpoint Composer itself hits, so it is fast and heavily cached.

Each version entry is essentially the package's composer.json at that release, including `require`, `require-dev`, autoload rules and licence. That makes it useful for dependency analysis without cloning anything.

Quick facts

Base URL
https://repo.packagist.org
Authentication
No API key required.
Rate limit
The /p2/ metadata endpoints are CDN-served and built for high volume. The search API on packagist.org is more limited.
Pricing
Free.
CORS
Not enabled — call it from your server
Official docs
Read the docs

How to use the Packagist API

Every request below was executed against the live API on 2026-08-19, and the response shown is the real body it returned — not an illustration.

1. Fetch all versions of a PHP package

GET https://repo.packagist.org/p2/monolog/monolog.json

curl
curl 'https://repo.packagist.org/p2/monolog/monolog.json'
JavaScript (fetch)
const res = await fetch("https://repo.packagist.org/p2/monolog/monolog.json");
if (!res.ok) throw new Error(`Request failed: ${res.status}`);
const data = await res.json();
console.log(data);
Python (requests)
import requests

res = requests.get("https://repo.packagist.org/p2/monolog/monolog.json", timeout=20)
res.raise_for_status()
print(res.json())
Response — HTTP 200 (truncated)
{
  "minified": "composer/2.0",
  "packages": {
    "monolog/monolog": [
      {
        "name": "monolog/monolog",
        "description": "Sends your logs to files, sockets, inboxes, databases and various web services",
        "keywords": [
          "log",
          "logging",
          "psr-3"
        ],
        "homepage": "https://github.com/Seldaek/monolog",
        "version": "3.10.0",
        "version_normalized": "3.10.0.0",
        "license": [
          "MIT"
        ],
        "authors": [
          {
            "name": "Jordi Boggiano",
            "email": "j.boggiano@seld.be",
            "homepage": "https://seld.be"
          }
        ],
        "source": {
          "url": "https://github.com/Seldaek/monolog.git",
          "type": "git",
          "reference": "b321dd6749f0bf7189444158a3ce785cc16d69b0"
        },
        "dist": {
          "url": "https://api.github.com/repos/Seldaek/monolog/zipball/b321dd6749f0bf7189444158a3ce785cc16d69b0",
          "type": "zip",
          "shasum": "",
          "reference": "b321dd6749f0bf7189444158a3ce785cc16d69b0"
        },
        "type": "library",
        "support": {
          "issues": "https://github.com/Seldaek/monolog/issues",
          "source": "https://github.com/Seldaek/monolog/tree/3.10.0"
        },
        "funding": [
          {
            "url": "https://github.com/Seldaek",
            "type": "github"
          },
          {
            "url": "https://tidelift.com/funding/github/packagist/monolog/monolog",
            "type": "tidelift"
          }
        ],
        "time": "2026-01-02T

Parameters

ParameterTypeRequiredDescription
p2/<vendor>/<package>.jsonpathRequiredVendor and package name. monolog/monolog
search.json?q=pathOptionalSearch packages on packagist.org. logging

Response fields

minifiedstring
Format marker, `composer/2.0` — versions are delta-compressed.
packages.<vendor/name>array
Array of version objects, newest first.
packages[].versionstring
Version string.
packages[].requireobject
Runtime dependencies with version constraints.
packages[].licensearray
SPDX licence identifiers.
packages[].autoloadobject
PSR-4 or classmap autoload configuration.

What you can build with the Packagist API

  • Check the latest release of a Composer package
  • Audit licences across a PHP project's dependencies
  • Analyse dependency constraints before upgrading
  • Build a package browser or version badge

Common errors and how to fix them

404

Unknown vendor/package pair.

Fix: Both parts are required and lowercase: monolog/monolog, not just monolog.

Fields missing on some versions

The /p2/ format is delta-compressed — omitted fields inherit from the previous entry.

Fix: Merge forward from the first entry rather than reading each version in isolation.

Packagist API — frequently asked questions

Is the Packagist API free?

Yes, completely free with no API key. The /p2/ metadata endpoints are CDN-served and designed to handle Composer's own traffic.

Why do some versions seem to be missing fields?

The /p2/ format is minified with delta compression — a version only lists what changed from the previous entry. Merge forward rather than treating each entry as complete.

How do I find the latest version?

The versions array is ordered newest first, so the first entry with a non-dev version string is the current release.

Can I search for packages?

Yes, via packagist.org/search.json?q=term, though that endpoint is more rate limited than the CDN-served metadata paths.

Tools that pair with this API

JSON Formatter

Format, beautify and minify JSON online with 2-space, 4-space or tab indentation. Sort keys alphabetically and catch syntax errors instantly — free and private.

JSON Validator

Free online JSON validator: validate JSON and find syntax errors with the exact line and column. See root type, key counts and depth — instant and 100% private.

Packagist is an independent third-party service and is not affiliated with ByteTools or ByteVancer. Details on this page were verified on 2026-08-19; always check the official documentation before relying on this API in production, as terms and limits can change.