What are HTTP response headers?
Every HTTP response carries metadata alongside its body — headers that tell the browser how to cache the response, what security policies to enforce, what server software handled the request, and what content type is being sent. You can't see these in a normal page load without opening browser dev tools, but they control real behavior: a missing cache-control header means assets re-download unnecessarily, a missing Content-Security-Policy leaves an XSS vector open, and Strict-Transport-Security decides whether a browser will ever downgrade a connection to plain HTTP.
This tool fetches a URL server-side and returns its response headers, so you can inspect them without needing a browser's network panel or a terminal.
When to use it
Use it to audit a production site's security headers (HSTS, X-Frame-Options, Content-Security-Policy, X-Content-Type-Options) after a deploy, to check whether a CDN or reverse proxy is setting the caching headers you configured, or to debug a CORS issue by confirming what Access-Control-Allow-Origin a server is actually sending. It's also a quick way to identify what's serving a URL — the Server and X-Powered-By headers (when present) often reveal the stack — or to confirm a redirect chain's final response.
Because the fetch happens from the server, not your browser, this also sidesteps CORS restrictions that would block a client-side fetch to a third-party domain.
Example
Enter example.com and Fetch returns a status of 200 alongside headers like content-type: text/html; charset=UTF-8, cache-control, and any security headers the site sets. Compare this against your own site's headers to spot ones you expected but that are missing — a common gap is forgetting to forward security headers through a CDN or load balancer configuration.
How to use the HTTP Headers Viewer tool
- 1
Enter a URL
Type or paste a domain or full URL — https:// is added automatically if omitted.
- 2
Click Fetch (or press Enter)
The server requests the URL and returns its response status and headers.
- 3
Review the header table
Each header name and value is listed, with the response status shown above it.
- 4
Share the result
Copy a permalink that restores the URL and re-fetches its headers for anyone who opens it.
Frequently asked questions
Does this run in my browser or on a server?
The fetch itself is proxied through a server-side API route, since a client-side fetch to an arbitrary third-party domain would usually be blocked by CORS. Only the URL you type is sent to that route — no other browsing data leaves your machine.
Why don't I see the headers I expect?
Some headers (like Set-Cookie) are stripped by browsers and fetch implementations before JavaScript ever sees them, and a CDN in front of the origin may add, remove, or rewrite headers compared to what your application server sends — what you see here is the final response as it left the network, not necessarily what your app code set.
Can I check headers for a URL requiring authentication?
No — the fetch is unauthenticated, so it reflects what an anonymous visitor (or crawler) would receive, not headers gated behind a login or API key.
Is this useful for debugging redirects?
It shows the headers of the response actually returned, which for a followed redirect chain is the final destination — if you need to inspect an intermediate redirect's own headers (e.g. its Location value), use your browser's network tab instead, which shows each hop.
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