Fastly Detector
Paste any URL and instantly see whether the site is built with Fastly — with the matched evidence.
We do not store the URL you audit. Want the full audit (performance / images / SEO / accessibility + real-browser speed test)? → run the full audit
Why check this
Confirm the platform first: Hosting & CDN decides what can be changed and whether it is worth it.
What this is
Fastly is a programmable edge CDN used by media, commerce and API acceleration teams. Confirming `x-fastly*` or `x-served-by: cache-*` lets you weigh VCL/Compute logic, shield POPs and whether login walls delay time to first byte. VCL and Compute logic can help or hurt time-to-first-byte depending on cache keys.
How to tell from a public page
- [Fastly] Response headers expose `x-fastly` prefixed fields.
- [Fastly] `x-served-by` follows a `cache-` node name.
- [Fastly] Debug headers reveal service ids or shield details.
- [Fastly] Error pages or synthetic responses show edge-generated traits.
How to read the result
Confirm when edge debug headers reproduce; a blog claiming we use the edge remains only suspected. Absence can mean production disabled edge debug headers. Tutorial responses with forged headers deserve skepticism. After a hit, inspect login walls and over-fragmented cache keys.
What to do next
Simplify cache keys, warm critical URLs, and compare with enterprise edge Akamai — jump to Akamai detector. Complete scoring on run the full performance / images / SEO / accessibility audit on the home page. Favour simpler cache keys before adding more VCL branches.
Related detectors
FAQ
How is Fastly detected?
From structural signatures in the public HTML and response headers (domains, paths, attributes, scripts). Every verdict lists how many times each pattern matched — nothing is guessed.
Can the result be wrong?
If only a bare brand keyword matches without structural evidence, we label it \u201clikely\u201d instead of \u201cconfirmed\u201d — we would rather under-report than cry wolf.
Do you save the URLs I check?
No. The audit runs inside the request and the URL you paste is not written to storage. There are no third-party tracking scripts on the page either, so no log of who checked what exists. Copy the result yourself if you want a record.
Can a website hide what it is built with?
Partly, but rarely completely. The HTML sent to your browser, the response headers, script paths and asset structure have to be exposed to work, so there is always something readable. Server-side code, build config and private APIs stay invisible. That is why this tool reports the evidence it found rather than claiming a full picture. No match does not mean the technology is absent.
Optimization help is available
Tell me your URL and what you want fixed — you get a clear scope, price and timeline.
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