HTTP Message Parser — Request, response, headers

Paste a raw HTTP/1.1 request, response, or header block and read the start-line, duplicate headers, and JSON body. Copy a request as cURL. This HTTP header parser runs in your browser, and nothing is sent or executed.

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HTTP Message Parser
Paste a raw HTTP/1.1 request, response, or header block. Read the start-line, every header row (duplicates kept), and the body. JSON pretty-print is display-only, not a JSON IDE.

Developer notes

RFC 9112 start-line: request, response (e.g. HTTP/1.1 200), or headers-only. LF and CRLF both accepted. Duplicate headers stay as separate rows (Set-Cookie). curl -v chatter is ignored when the start-line is cheap to find. Copy as cURL emits the DevTools subset from a parsed request. Sanitize on that copy (off by default) does not strip the table. JSON bodies can be pretty-printed inline; validate/repair stays on JSON Formatter / JSON Validator. No chunked reassembly, no HTTP/2 frames, no request execution.

Options

JSON body view
pretty (default when the body is JSON) or raw. Display only, not a JSON editor.

When this is the right tool

Read a captured HTTP/1.1 200 and pretty-print the JSON body. Keep both Set-Cookie lines instead of collapsing them. Parse a header block without a start-line.

Worked examples

HTTP/1.1 200 + JSON body

Before

HTTP/1.1 200 OK\nContent-Type: application/json\n\n{"ok":true,"items":[1]}

After

Start-line HTTP/1.1 200 OK; JSON body pretty-printed when the toggle is on.

Duplicate Set-Cookie

Before

HTTP/1.1 200 OK\nSet-Cookie: a=1\nSet-Cookie: b=2

After

Two header rows, both kept, not merged into one Cookie line.

Related HTTP and JSON tools

Back to the HTTP Tools hub. Format the JSON body in JSON Formatter or check it with JSON Validator. For tokens, use JWT Decode. Parse Set-Cookie with Cookie / Set-Cookie Parser. For specs, see API & schema tools.

HTTP Message Parser FAQ

Request, response, and headers, local only

Is this an HTTP header parser?

Yes, headers-only blocks work. The same engine also parses full requests and responses. There is no separate headers-only slug.

Are duplicate headers kept?

Yes. Each line is a row, including multiple Set-Cookie headers.

Does pretty-print validate JSON?

No. The toggle only changes display. Use JSON Validator to check or repair JSON.

Does this send the message?

No. FastMinify never executes the request. There is no Send control.

What does Copy as cURL do?

It builds a DevTools-subset cURL command from the parsed request (method, URL, headers, body). Optional Sanitize copy (off by default) strips Cookie, Authorization, sec-ch-*, and Referer from the clipboard only, and the table still shows those rows. Responses and headers-only pastes cannot become cURL.

HTTP Tools

Paste-local cURL, HTTP messages, URLs, HAR files, and Cookie / Set-Cookie headers — format and inspect in your browser, never sent.

Explore other tool categories