cdnjs API

Free cdnjs API with no key: search 4,000+ front-end libraries, get versions, file listings and SRI hashes for secure script tags. Tested curl example.

No API key requiredCORS enabledHTTPSFree tier

Endpoint tested and returned HTTP 200 on 20 Aug 2026

What is the cdnjs API?

The cdnjs API is a free, key-free API for the cdnjs content delivery network, providing metadata for over 4,000 front-end libraries including every version, the files each ships and Subresource Integrity hashes.

cdnjs is one of the oldest and most widely used front-end CDNs, and its API exposes the full library catalogue — useful for building version pickers, checking for updates, or discovering what a library actually ships.

The SRI hashes are the security-relevant part. Including an integrity attribute on a CDN script tag means the browser refuses to execute the file if it has been tampered with, and cdnjs provides those hashes directly so you do not have to compute them.

Quick facts

Base URL: https://api.cdnjs.com
Authentication: No API key required.
Rate limit: No published hard limit; CDN-backed.
Pricing: Free and open source, operated by Cloudflare.
CORS: Enabled — callable directly from browser JavaScript
Official docs: Read the docs

How to use the cdnjs API

Every request below was executed against the live API on 20 Aug 2026, and the response shown is the real body it returned — not an illustration.

1. Fetch metadata for a library

GET https://api.cdnjs.com/libraries/jquery?fields=name,version,description

curl

curl 'https://api.cdnjs.com/libraries/jquery?fields=name,version,description'

JavaScript (fetch)

const res = await fetch("https://api.cdnjs.com/libraries/jquery?fields=name,version,description");
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://api.cdnjs.com/libraries/jquery?fields=name,version,description", timeout=20)
res.raise_for_status()
print(res.json())

Response — HTTP 200

{
  "name": "jquery",
  "description": "JavaScript library for DOM operations",
  "version": "4.0.0"
}

Parameters

Parameter	Type	Required	Description
`libraries/<name>`	path	Optional	Metadata for one library. `libraries/jquery`
`libraries`	path	Optional	Search or list libraries. `libraries?search=chart`
`fields`	string	Optional	Comma-separated fields to return — responses are huge without it. `name,version,description`
`search`	string	Optional	Search term. `chart`

Response fields

namestring: Library name.
versionstring: Latest version available.
descriptionstring: Library description.
homepage / repositorystring: Project links.
licensestring: Licence identifier.
assetsarray: Every version with its file list and SRI hashes.
sriobject: Subresource Integrity hashes keyed by filename.

What you can build with the cdnjs API

Build a CDN script tag generator with integrity hashes
Check whether a front-end library has a newer version
Discover which files a library ships before including one
Search available libraries from a build tool

Common errors and how to fix them

Enormous response

Without `fields`, every version and file is returned.

Fix: Always pass fields= with just what you need; jQuery's full record is megabytes.

404

Library name not found.

Fix: cdnjs names do not always match npm names; use the search endpoint first.

Missing SRI hash

Older versions predate SRI generation.

Fix: Fall back to omitting the integrity attribute, or pick a newer version.

cdnjs API — frequently asked questions

Is the cdnjs API free?

Yes, completely free with no API key. cdnjs is operated by Cloudflare as a community service.

What is an SRI hash and why does it matter?

A Subresource Integrity hash lets the browser verify a CDN file has not been tampered with, refusing to execute it if the content changed. cdnjs provides these so you can add integrity attributes to script tags.

Why is the response so large?

By default it returns every version with every file. Always use the `fields` parameter to request only what you need.

Do cdnjs names match npm names?

Usually but not always. Use the search endpoint to resolve a name before assuming the npm package name works.

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.

SHA-256 Hash Generator

Generate SHA-256 hashes of text or files with the browser's Web Crypto API. 64-character hex digest, uppercase option, instant copy. Free and private.

Alternatives to cdnjs API

If cdnjs does not fit, these developer & testing apis cover similar ground. Every one was called before publishing, and each links to its own reference page with a working curl command and the response it returned.

API	What it does	Auth	CORS	Last verified
GitHub REST API	GitHub REST API with no key for public data: repository details, users, issues, releases and commits. 60 req/hour unauthenticated, 5,000 with a token.	No key	Yes	19 Aug 2026
JSONPlaceholder	Free fake REST API for testing and prototyping. Posts, comments, users and todos with full GET, POST, PUT and DELETE support. No key. Real curl examples.	No key	Yes	19 Aug 2026
Postman Echo	Postman Echo reflects your HTTP request back as JSON: headers, body, query params and auth. Free, no key, ideal for debugging clients. Real POST example.	No key	No	19 Aug 2026
DummyJSON	Free fake REST API with realistic products, users, carts, recipes and auth. Supports search, pagination, sorting and POST. No key. Tested GET and POST examples.	No key	Yes	19 Aug 2026
Cloudflare Trace	Free Cloudflare trace endpoint with no key: your IP, country, data centre, TLS version, HTTP protocol and user agent as plain text. Instant, no signup. Tested.	No key	Yes	20 Aug 2026
CocoaPods Trunk	Query the CocoaPods Trunk API for a pod's published versions and release timestamps with no key. Includes the non-ISO date format and version-ordering gotchas.	No key	No	21 Aug 2026

All Developer & Testing APIs

cdnjs is an independent third-party service and is not affiliated with ByteTools or ByteVancer. Details on this page were verified on 20 Aug 2026; always check the official documentation before relying on this API in production, as terms and limits can change.