HTTP Header Parser

How to use HTTP Header Parser

1. Open HTTP Header Parser — it runs entirely in your browser with no setup.
2. Paste or type your input into the text area, or upload a file where supported.
3. Set any options you need. The result appears in the output panel — there is no upload step and no waiting on a server.
4. Review the output instantly; large inputs are handled locally without lag.
5. Copy the result to your clipboard or download it. Your data never leaves the page.

Why use HTTP Header Parser?

• 100% free with no limits, no sign-up and no watermarks.
• Private by design — your data are processed in your browser and never uploaded to a server.
• Fast and lightweight, with instant results even on a phone or a slow connection.
• Works everywhere — any modern browser on Windows, macOS, Linux, Android or iOS.
• Part of a full developer tools suite, so related http header parser tasks are one click away.

What people use HTTP Header Parser for

• Reading a raw response captured from curl or a proxy.
• Checking which security headers a response actually carries.
• Debugging caching behaviour by inspecting Cache-Control and ETag.

HTTP Header Parser: limits and things worth knowing

• Header names are case-insensitive, so Content-Type and content-type are the same header. HTTP/2 and HTTP/3 send them lowercase, which is why captures look different from HTTP/1.1.
• Some headers may legitimately repeat — Set-Cookie above all — and must not be collapsed into one comma-joined value the way most others may be.
• The order of headers is not significant, with the exception of multiple Set-Cookie lines, which are applied in order.
• A folded header continued on an indented line is obsolete and rejected by modern servers, but still appears in old captures and documentation.

Is it private and secure?

Your privacy is built in. HTTP Header Parser runs completely on your device, so whatever you enter stays in your browser and is never transmitted, logged or stored on any server.

Network activity: none. Nothing is sent and nothing is fetched. This tool makes no network request at all once the page has loaded — which is why it keeps working if your connection drops.

You do not have to take that on trust — our privacy proof page publishes the Content-Security-Policy that enforces it, lists every third party it permits, and shows how to verify the whole claim yourself.

Learn more

Is It Safe to Paste Production Data Into Online Tools? — JWTs, API responses and env files get pasted into online formatters every day. Here's what actually happens to that data and how to check before you paste.