What is the structure of an HTTP message?

Every HTTP message has a start line (request line or status line), zero or more headers, a blank line, and an optional body. The blank line is mandatory and separates headers from the body.

What is the difference between a request and response message?

A request starts with METHOD URL VERSION (e.g. GET /api HTTP/1.1). A response starts with VERSION STATUS REASON (e.g. HTTP/1.1 200 OK).

What does the blank line in HTTP mean?

The blank line (CRLF) marks the end of headers and the beginning of the message body. It is required even if there is no body.

Tools

HTTP Message Parser

Paste a raw HTTP request, response or curl -v transcript to see it parsed, checked against the RFCs, and linked to the reference page for every header and status code.

Raw HTTP message

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Parsed output appears here as you type. Paste a message above or pick a sample.

HTTP Message Format

Every HTTP message follows the same structure: a start line, headers, a blank line, and an optional body. Learn more in the How HTTP Works guide or exploreHTTP methods, headers, and status codes. Try the HTTP Playground to send real requests, or theHeader Inspector to see what a live site returns.