What is the BlueAT CDN
The BlueAT Network offers an alternative to the Bluesky CDN that's just as fast but powered by Cloudflare Workers with extra features. The BlueAT CDN is a drop in replacement for the Bluesky CDN that's powered by Cloudflare Workers, transforms images to the .AVIF format and caches it on the Cloudflare Network for 7 days.
How it Works
1. Request A request arrives for a path like /img/avatar/plain/did:plc:…/cid@jpeg — the same URL format used by cdn.bsky.app. The DID and CID are extracted from the path.
2. Cloudflare cache check Before doing any resolution work, the Worker checks Cloudflare's Cache API. If the blob has been fetched before, it's served instantly from the edge with no further processing.
3. DID resolution On a cache miss, the Worker resolves the DID to find the user's PDS. For did:plc, it queries the PLC directory. For did:web, it fetches the /.well-known/did.json document directly.
4. Blob fetch The blob is fetched from the PDS using com.atproto.sync.getBlob. If the CID has rotated (e.g. a new profile picture), the current one is looked up first via com.atproto.repo.getRecord.
5. Cache and serve The response is streamed back to the client and stored in Cloudflare's Cache API with a 7-day TTL. Future requests for the same blob are served entirely from the edge, bypassing the PDS entirely.
Try it with witchsky.app
- Open witchsky.app and go to Settings
- Navigate to the Runes section
- Find the Custom CDN field and enter https://cdn.blueat.net
- Save — images will now load directly from users' PDSes via this worker