Why are some headers marked as repeated?

Because the same field name appears more than once. Some headers, like Set-Cookie, are supposed to repeat and must not be merged; others are combined by the recipient. The label shows you which is which before you act on the values.

How are folded lines handled?

Older systems wrapped long header values onto the next line with leading whitespace. The parser treats a line that starts with a space or tab as a continuation of the previous header and joins it back with a single space, which is what the HTTP rules say to do.

What is the status line?

The HTTP/1.1 200 OK line that opens a response. It is optional here, so you can paste just the headers, but when it is present it is reported separately and not mistaken for a header.

Is anything sent over the network?

No. The text you paste is parsed in the page. That is deliberate: header blocks often carry cookies, tokens and internal hostnames that should not leave your machine.

HTTP Header Parser

Raw header block

Paste the header block from curl -I, a proxy log or the browser network panel. A status line is optional, folded continuation lines are joined, and repeated fields such as Set-Cookie are kept and labelled. Nothing is sent anywhere.

Summary

Headers

Learn

HTTP Header Parser Guide

About this tool

Paste a raw header block from curl, a proxy log or the browser network panel and the page turns it into a clean table. A status line is optional, folded continuation lines are rejoined, and repeated fields such as Set-Cookie are kept and marked so nothing is silently dropped.

Questions

Why are some headers marked as repeated?: Because the same field name appears more than once. Some headers, like Set-Cookie, are supposed to repeat and must not be merged; others are combined by the recipient. The label shows you which is which before you act on the values.
How are folded lines handled?: Older systems wrapped long header values onto the next line with leading whitespace. The parser treats a line that starts with a space or tab as a continuation of the previous header and joins it back with a single space, which is what the HTTP rules say to do.
What is the status line?: The HTTP/1.1 200 OK line that opens a response. It is optional here, so you can paste just the headers, but when it is present it is reported separately and not mistaken for a header.
Is anything sent over the network?: No. The text you paste is parsed in the page. That is deliberate: header blocks often carry cookies, tokens and internal hostnames that should not leave your machine.

HTTP Header Parser