HTTP Header Inspector
Fetches a URL and shows the full response headers, redirect chain, timings and compression used.
One request to a URL, and every response header it comes back with — grouped by what they are for, with Cache-Control broken into its directives and each one explained. It is what a browser sees before it renders anything, which is where cache and compression problems actually live.
Our server makes this request for you. Only the URL you typed is sent to it — none of your cookies or login state goes along. The server will only connect to public addresses and refuses private and internal ones.
How to use it
Give it the URL you actually want
Up to five redirects are followed and the headers shown are the last response’s. If you care about the redirect itself, the chain is drawn above with the status of each hop.
Read the notes before the tables
Each note is derived from a specific header — a missing Cache-Control, an Expires that max-age overrides, an HTML response with no charset. They are the findings; the tables are the evidence.
Check the compression line
The request offers gzip, deflate, br, and zstd; what comes back is what the server chose. A text response with no Content-Encoding is usually 70% larger than it needs to be.
Common questions
Does my login or cookie go with the request?
No. Our server makes the request, so it carries none of your cookies and none of your session. That also means a page behind a login will come back as its sign-in page rather than the version you see.
Can I check something on my own network?
No, and deliberately. The outbound fetch resolves the host first and refuses private, loopback and link-local addresses — including a public name that resolves to one. Without that rule this page would be a way to make our server probe the inside of someone else’s network.
The headers differ from what devtools shows me
Expect that. A CDN varies its answer by geography, by Accept-Encoding, by Vary, and by whether it has a cached copy for that edge. This is one request from one place; your browser is a different one.
Why is Content-Length missing?
Chunked transfer encoding, almost always — the server started sending before it knew the size. It is normal for dynamic pages, and it is why a download from them shows no progress percentage.
Feed it from
MIME Type Lookup
Looks up a MIME type from an extension or the other way round, and sniffs the type from file bytes.
HTTP Status Reference
Explains every status code with its spec meaning, cacheability and the mistakes people make with it.
User-Agent Parser
Breaks a user-agent string into browser, engine, OS and device, and shows your own for comparison.
HAR Viewer & Sanitiser
Opens a HAR capture as a waterfall and strips cookies, auth headers and tokens before you share it.
Next
These accept what this tool produces, so the result can go straight in.
HTTP Status Reference
Explains every status code with its spec meaning, cacheability and the mistakes people make with it.
Security Header Scan
Grades a site’s HSTS, CSP, frame, referrer and permissions headers and shows what to add.
SSL Certificate Checker
Connects to a host, shows the served chain, expiry, protocol and cipher support, and flags chain gaps.
Redirect Chain Tracer
Follows a shortened or tracking URL through every redirect and shows the final destination.
HTTP Request Builder
Composes and sends a GET/POST/PUT/PATCH/DELETE/HEAD request with custom headers and a body, and shows the status, headers, body and timing — without ever forwarding cookies or Authorization.
Barcode Generator
Generates EAN-13, UPC, Code128, Code39 and ITF barcodes with check digits and print-ready output.