How to Read HTTP Headers: Analyze Response Headers Online

HTTP headers carry the hidden metadata behind every request and response, and reading them tells you exactly how a server handles caching, compression, cookies, and security. If you have a wall of raw headers and no idea what each line means, paste them into the HTTP Header Analyzer and get a plain-English breakdown of each one.

What HTTP headers tell you

Response headers are the server talking back about how to treat its content. The ones that matter most:

Status and Content-Type: the response code and the format of the body, like text/html or application/json.
Cache-Control: how long browsers and CDNs may store the response, and whether they must revalidate.
Content-Encoding: whether the body is compressed with gzip or brotli to save bandwidth.
Security headers: Strict-Transport-Security (HSTS), Content-Security-Policy (CSP), and X-Content-Type-Options, which harden the site against common attacks.
Set-Cookie: cookies the server wants stored, including flags like Secure, HttpOnly, and SameSite.
Server: the software behind the response, which sometimes leaks more than it should.

How to get the raw headers

The analyzer reads headers you paste in, so first grab them. Two quick ways:

Run curl -I https://example.com in a terminal to print just the response headers.
Open your browser DevTools, go to the Network tab, click the request, and copy the Response Headers block.

Either gives you the raw text you need.

Analyze your HTTP headers in three steps

Open the HTTP Header Analyzer.
Paste the raw response headers from curl or DevTools.
Read the plain-English explanation for each header, grouped by caching, compression, content, and security.

Everything runs in your browser. The tool does not fetch any URL or send your headers anywhere, so pasted data stays on your device.

Common things headers reveal

Once you can read them, headers answer real questions fast. A missing Cache-Control or a no-store value explains why a page never caches. No Content-Encoding means responses are not compressed and could be smaller. An absent Strict-Transport-Security or X-Content-Type-Options header flags a security gap. A Set-Cookie without Secure or HttpOnly points to a cookie that needs hardening. Reading the headers turns guesswork into a clear checklist.

HTTP Status Code Reference: look up what that 301, 403, or 502 in the status line actually means.
Security Headers Generator: build the HSTS, CSP, and other headers your analysis says are missing.
CORS Header Validator: check that your cross-origin headers are set up correctly.

Paste your headers, read the breakdown, and you will know exactly what a server is doing in seconds.