HTTP Header Parser
Paste a raw HTTP request or response header block and get a structured, case-normalized map of every header. Choose the name casing, fold repeated headers your way, and keep Set-Cookie as a list. Runs in your browser; nothing is uploaded.
About this tool
Paste a raw HTTP request or response header block and this tool turns it into a
clean, structured JSON map of name → value. It is built for the moment you
copy a jumble of headers out of your browser's network panel, a curl -i
dump, or a log line and want them as tidy, comparable data instead of loose
text.
Header names are matched case-insensitively (HTTP treats Content-Type,
content-type, and CONTENT-TYPE as the same field) and then re-cased to the
style you pick: canonical Title-Case like Content-Type, all lowercase, all
UPPERCASE, or the original casing exactly as you pasted it. Repeated headers
are folded by a policy you choose — combine them into one comma-joined value
per RFC 7230, keep every occurrence as a JSON array, or keep just the first or
last. Set-Cookie is never comma-joined (RFC 6265 forbids it), so under the
combine policy it always stays a list.
An optional leading request line (GET /path HTTP/1.1) or status line
(HTTP/1.1 200 OK) is detected and captured separately, so you can paste a
whole response head without hand-trimming it first. Parsing stops at the first
blank line — the head/body boundary — so a pasted body is ignored. The result
also reports the detected message kind, the number of distinct headers, the raw
line count, and which header names were duplicated.
Everything runs locally in your browser through a small WebAssembly module. Nothing is uploaded, so it is safe to paste headers that carry cookies, tokens, or other sensitive values.
Example
Paste this response head:
HTTP/1.1 200 OK
Content-Type: text/html; charset=utf-8
Cache-Control: max-age=60
Set-Cookie: id=1; Path=/
Set-Cookie: sess=xyz; HttpOnly
With canonical casing and the combine policy you get:
{
"kind": "response",
"start_line": "HTTP/1.1 200 OK",
"case": "canonical",
"duplicate_policy": "combine",
"headers": {
"Content-Type": "text/html; charset=utf-8",
"Cache-Control": "max-age=60",
"Set-Cookie": ["id=1; Path=/", "sess=xyz; HttpOnly"]
},
"count": 3,
"line_count": 4,
"duplicates": ["Set-Cookie"]
}
FAQ
How does it handle repeated headers like Set-Cookie?
You choose the policy. Combine (the default) joins repeated values with
, as allowed by RFC 7230 — except Set-Cookie, which stays a JSON array
because RFC 6265 forbids folding cookies onto one line. List keeps every
header as an array of all its values. First and last keep only that one
occurrence. Any name that appeared more than once is also listed in the
duplicates field.
Do I need to strip the request or status line first?
No. A leading request line such as GET /path HTTP/1.1 or a status line such
as HTTP/1.1 200 OK is detected automatically, reported in kind, and
returned separately in start_line. If the block has no start line the kind
is simply headers. Paste whatever you copied.
What does the casing option change?
Only how names are written in the output — matching is always
case-insensitive. Canonical renders standard HTTP Title-Case
(content-type → Content-Type, with special cases like ETag and
WWW-Authenticate). lower and upper force a single case, which is handy
for diffing two header sets. original keeps the exact casing you pasted for
the first occurrence of each name.
Can I paste a full response including the body?
Yes. Parsing follows the HTTP rule and stops at the first blank line, which separates the head from the body, so anything after it is ignored. It also accepts both CRLF and bare-LF line endings and joins obsolete folded continuation lines (a line that begins with a space or tab) onto the header above them.
Is my data sent anywhere?
No. The parser is a WebAssembly module that runs entirely in your browser. The header text never leaves your machine, so pasting cookies, authorization tokens, or other sensitive header values is safe.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool http-header-parser "HTTP/1.1 200 OK
Content-Type: text/html; charset=utf-8
Cache-Control: max-age=60
Set-Cookie: id=1; Path=/
Set-Cookie: sess=xyz; HttpOnly"New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/http-header-parser/?headers=HTTP%2F1.1%20200%20OK%0AContent-Type%3A%20text%2Fhtml%3B%20charset%3Dutf-8%0ACache-Control%3A%20max-age%3D60%0ASet-Cookie%3A%20id%3D1%3B%20Path%3D%2F%0ASet-Cookie%3A%20sess%3Dxyz%3B%20HttpOnly&case=canonical&duplicates=combineMachine-readable descriptor: tool.json — title + parameters JSON Schema for agents.