usefulweb.site CDN Behaviour Explorer

Internet infrastructure explorers

CDN Behaviour Explorer

Which CDN serves a URL, whether it caches it (HIT/MISS, Age, TTL) and how, from two requests.

Try an example: Cloudflare MISS then HIT (pasted)

How it works

Sends two consecutive requests to a public URL (or reads two pasted header sets) and compares them: CDN detection from vendor headers (Cloudflare, CloudFront, Fastly, Akamai, Vercel, Netlify, Bunny, Azure, Google), edge cache status HIT/MISS/EXPIRED, Age progression, edge location, shared-cache TTL, Vary and compression. Only this server's vantage point is used; there is no multi-region comparison.

  • Live mode: two GET requests in a row through the SSRF-guarded fetcher (body capped at 64 KiB each), identical request headers.
  • CDN detection from vendor headers: cf-ray/cf-cache-status (Cloudflare), x-amz-cf-id/x-amz-cf-pop (CloudFront), x-served-by cache-xxx/x-fastly-request-id (Fastly), akamai-grn/x-akamai-*/AkamaiGHost (Akamai), x-vercel-id, x-nf-request-id, BunnyCDN, x-azure-ref, Via: google.
  • Cache status from the vendor header or RFC 9211 Cache-Status (the last listed cache is closest to the client); Age (RFC 9111 §5.1) growing between requests means one stored copy answered both.
  • TTL: CDN-Cache-Control / Surrogate-Control > s-maxage > max-age > Expires − Date. Browser TTL is max-age.
  • Region comparison is not available: tools run from one server. HeaderLens has multi-region probe agents, but they are not wired into tools.

For scripts and AI agents

  • JSON API: POST https://cdnbehaviorexplorer.usefulweb.site/api/v1/calculate (same calculation as this page)
  • Interface description: OpenAPI 3.1 · AI guide: llms.txt
  • MCP server (Streamable HTTP): https://cdnbehaviorexplorer.usefulweb.site/mcp · tool name cdn_behavior_explorer
Example request
curl -s -X POST https://cdnbehaviorexplorer.usefulweb.site/api/v1/calculate \
  -H 'content-type: application/json' \
  -d '{…see OpenAPI examples…}'

Related tools

  • HTTP Technology Explorer – Headers, compression, caching, HTTP/2-3 hints, redirects, security and tech stack for a URL.
  • HeaderLens – Is a website down? Multi-region status, redirects, TLS and security headers.
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