Cloudflare Migrates cdnjs to Its Developer Platform, Serving 9 Billion Daily Requests

cdnjs Migrates to Cloudflare Developer Platform

Cloudflare has completed the migration of cdnjs, its open-source CDN for JavaScript and CSS libraries, to its Developer Platform. This move consolidates the service's infrastructure, which previously relied on a mix of Cloudflare and Google Cloud Platform services, onto Cloudflare's serverless offerings.

The migration involved replacing components like Google Cloud Functions, Google Cloud Storage, and Pub/Sub with Cloudflare's Workers, R2, Workflows, Queues, Durable Objects, KV, and Containers. This change positions R2 as the primary source of truth for published package files, while maintaining existing URLs, package contents, and Subresource Integrity (SRI) hashes.

Scale and Impact of cdnjs

cdnjs handles approximately 9 billion requests per day, averaging 108,000 requests per second across more than 330 Cloudflare data centers. The service reports a 98.6% cache hit rate and is utilized by about 12% of websites globally. Cloudflare cited this migration as an example of using its own Developer Platform to support a widely used public service at scale.

Architectural Evolution

This migration builds upon a 2020 architectural update where Cloudflare moved cdnjs file serving to Workers and Workers KV, replacing dedicated origin machines for normal traffic. That update also introduced precompressed Brotli and gzip assets to enhance delivery efficiency. However, the publishing pipeline remained distributed across various Google Cloud services.

New Publishing and Serving Architecture

In the new architecture, Cloudflare R2 serves as the source of truth for published files, with KV storing package metadata, versions, and SRI hashes. A Worker handles requests, and Workers Cache provides the caching layer. Published content is also mirrored to DigitalOcean Spaces for fallback purposes.

Package ingestion is now managed by Cloudflare Workflows. A scheduled workflow checks npm and GitHub for new releases, downloads packages into R2, and initiates processing workflows for individual files. This processing pipeline extracts package contents, minifies and compresses assets, stores them in R2, updates metadata in KV, and refreshes the Algolia search index.

Previous Infrastructure Details

Prior to this migration, the cdnjs publishing path was distributed. Google Cloud Functions periodically checked npm for package releases, Google Cloud Storage held packages, and Pub/Sub managed messaging. A virtual machine running git-sync synchronized repository content. The system used 26 Cloud Functions, divided into alphabetic shards, to monitor package updates. The GitHub repository had grown to over 1.1 TB of packed storage, with published files duplicated in both GitHub and KV.