Cdnjs

What it is

cdnjs is a free, community-run CDN for open-source web-library assets, delivered through Cloudflare. Consumers select a library, exact version and file, then reference its public URL; the service also exposes library metadata through an API. Example markup published by Cloudflare uses a versioned URL and Subresource Integrity attributes. cdnjs' code repository is MIT-licensed, but each distributed library keeps its own license. It is a dependency-delivery service rather than private storage, a package-security review or a contractual availability guarantee.

Key features

• Library catalog

  Indexes versioned files from supported open-source JavaScript and CSS libraries.

• Cloudflare delivery

  Serves cached public assets through Cloudflare's network.

• API access

  Exposes library, version and file metadata for discovery and tooling.

• Integrity-ready snippets

  Provides examples and hashes that can be used with browser SRI and crossorigin attributes.

Strengths and trade-offs

Who it is for

Front-end developers who need simple public delivery of a supported open-source dependency and can pin, audit and fall back from that dependency.

Pick it or skip it

Frequently asked questions

What is cdnjs, and does it cost anything?

cdnjs is a free, open-source CDN for popular JavaScript, CSS and font libraries, run by Cloudflare and served from its 330+ edge locations; it handles more than 250 billion requests a month and is used by roughly 12.5% of websites. You reference a library by URL with no build step, and every script and link tag comes with a Subresource Integrity hash; content is HTTPS-only and HSTS-preloaded. To add a library you open a pull request with a JSON config in the cdnjs/packages repository; after approval, new versions are pulled automatically from npm or GitHub.

Is cdnjs free to use?

Yes. cdnjs describes itself as a free, open-source CDN for the web's most popular JavaScript, CSS and font resources, with no account or payment required.

Who runs and pays for cdnjs?

Every file is served directly from Cloudflare's global network, with Cloudflare providing the infrastructure and maintenance. The project is funded by Cloudflare, Algolia, DigitalOcean, Statuspage, Sentry and UptimeRobot.

How widely used is cdnjs?

The project reports more than 250 billion requests per month and use on 12.5% of all websites.

How much does Cdnjs cost?

Cdnjs is free to use. We verified this against the vendor's own page; see "What we checked" below for the date.

Does Cdnjs have a free plan?

Yes. Cdnjs is free to use at its base level.

Who is Cdnjs best for?

Front-end developers who need simple public delivery of a supported open-source dependency and can pin, audit and fall back from that dependency.

What are the main drawbacks of Cdnjs?

The trade-offs we noted: Catalog scope is narrow: It is not private asset storage or a general-purpose origin/CDN product.; Package trust remains external: CDN availability does not prove that a library release or transitive code is safe.; Third-party dependency: Page delivery, privacy posture and CSP must account for requests to an external domain..

When should you not use Cdnjs?

Skip Cdnjs if: You need a contractual bandwidth or rate-limit guarantee — none is published; Your compliance rules forbid loading assets from a third-party network you have no agreement with; You depend on a sponsor-funded service staying free; funding comes from donated infrastructure.