CDN detector. From response headers.
Paste raw response headers (curl -I or DevTools). We identify the CDN by signature header (cf-ray, x-vercel-id, x-served-by, x-cache, via) plus its tier evidence. Detects 20+ CDNs and edge platforms.
Paste HTTP response headers from curl -I https://example.com or browser DevTools. The detector matches against signature headers for 20+ CDNs (Cloudflare, Fastly, CloudFront, Vercel, Netlify, Akamai, Bunny, KeyCDN, Sucuri, StackPath) and reports the CDN plus the evidence header that identified it.
How do I get my response headers?
- curl:
curl -I https://example.com - Browser DevTools: F12 → Network tab → click the document request → Headers panel → copy the Response Headers block
Sources used
- Cloudflare HTTP headers reference — cf-ray, cf-cache-status, server
- Fastly headers documentation — x-served-by, x-cache, x-cache-hits, fastly-debug
- AWS CloudFront request/response behavior — x-amz-cf-id, x-amz-cf-pop
- Vercel Edge Network headers — x-vercel-id, x-vercel-cache, server
- Netlify CDN API — x-nf-request-id, server
- RFC 9110 §7.6.3 Via header — proxy/CDN identification per HTTP semantics
No data is sent to any external service. Detection happens entirely in your browser via signature pattern matching against the CDN documentation linked above.
Privacy: parsing happens in your browser. Nothing is sent or logged.
CDN is an SEO decision.
CDN choice affects the Core Web Vitals trio Google uses as ranking signals. LCP (Largest Contentful Paint) drops 30-60% with a quality CDN serving from edge close to the user vs origin-only. TTFB drops dramatically (often 200-400ms saved on first byte for global users). The detector above identifies the CDN behind the headers, plus the evidence header that proved it, so you can audit a site's edge stack before recommending changes.
Three rules of thumb for CDN selection. Pick Cloudflare for global free + WAF + bot protection — the default for most non-enterprise sites. Pick Vercel Edge or Netlify CDN for Next.js / JAMstack workflows where build-deploy integration matters more than raw edge density. Pick Fastly for high-traffic news + commerce where VCL configurability + per-request control are required.
Tools in the same cluster: HTTP Headers Checker for the broader header audit. Web Server Detector for the origin behind the CDN. Core Web Vitals Checker for the LCP / INP / CLS impact view.
Five answers.
How does the CDN detector work?
Each CDN injects characteristic headers into responses that pass through its edge. Cloudflare adds cf-ray and cf-cache-status. Fastly adds x-served-by and x-cache. CloudFront adds x-amz-cf-id and x-amz-cf-pop. Vercel adds x-vercel-id and x-vercel-cache. Netlify adds x-nf-request-id. The detector matches your pasted headers against the signature library for 20+ CDNs and reports the match plus the evidence header. Some sites front a CDN with another CDN — the detector flags multi-CDN stacks too.
Which CDNs can it identify?
Cloudflare, Fastly, Amazon CloudFront, Vercel Edge, Netlify CDN, Akamai, BunnyCDN, KeyCDN, Sucuri (security CDN), StackPath, Imperva (Incapsula), jsDelivr, cdnjs (Cloudflare), Azure CDN, Google Cloud CDN, Alibaba Cloud, Tencent CDN, MaxCDN, ArvanCloud, Section.io, Edgio (Limelight). For platforms-as-CDN: Shopify (origin Shopify-fronted Fastly), Squarespace (Fastly), WP Engine (Fastly), Webflow (Fastly via AWS). Self-hosted nginx-cache and Varnish detection by Via header.
Why does CDN choice matter for SEO?
CDN affects the Core Web Vitals trio that Google uses as ranking signals. LCP (Largest Contentful Paint) drops 30-60% with a quality CDN serving from edge close to the user vs origin-only. TTFB drops dramatically (often 200-400ms saved on first byte for global users). The CDN also affects security posture (DDoS protection, WAF, bot-management) and developer-experience (Vercel + Netlify ship build-deploy integrations that Cloudflare and CloudFront require more setup for). Identifying the CDN tells you what tier the site is on and whether a swap could deliver immediate Core Web Vitals lift.
What if no CDN is detected?
Three possibilities. One, the site has no CDN — typical for small WordPress + nginx setups, internal tools, and unoptimized sites. The performance impact is real (TTFB 1-3 seconds for cross-region users vs 100-300ms with CDN). Two, the CDN strips its identifying headers (rare but possible for security-conscious enterprises). Three, the headers were captured from a non-edge cached path. Try pasting headers from multiple URLs on the site (homepage + a deep page) — CDN edge caching status can vary per URL.
Does this tool save my data?
No. Header parsing happens in your browser. Nothing is sent to any server. Closing the tab clears the data. The Copy Results button puts a plain-text summary on your clipboard.
No CDN behind your site?
Our web development engagements ship the right CDN tier for your stack — Cloudflare for general-purpose, Vercel Edge for Next.js, Fastly for high-traffic commerce — with full Core Web Vitals optimization.
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