HTTP Header Reference
Searchable guide to common HTTP headers.
How to use
- 1 Type part of a header name or description in the search box.
- 2 Optionally filter to request-only or response-only headers.
- 3 Read the description and direction for each matching header.
- 4 Copy the ready-made "Header: value" example for any entry.
About HTTP Header Reference
The HTTP Header Reference is a fast, searchable cheat sheet for the request and response headers you meet every day when building and debugging web applications and APIs.
Instead of jumping to a spec or a wiki, you can type a fragment such as "cache", "cookie" or "security" and instantly see the matching headers, what each one does in plain English, whether it travels on the request or the response, and a realistic example value you can copy with one click.
It covers the headers that come up constantly: content negotiation with Accept and Content-Type, caching with Cache-Control, ETag, Last-Modified and the conditional If-None-Match, authentication with Authorization and WWW-Authenticate, cookies with Cookie and Set-Cookie, and the security headers that harden a site such as Strict-Transport-Security, Content-Security-Policy, X-Content-Type-Options and X-Frame-Options.
You can also filter the list to just request or just response headers when you are reasoning about one side of an exchange.
Every example is formatted as a complete "Header: value" line, so you can paste it straight into a curl command, a fetch call, a test fixture or a server config and adjust from there.
The reference runs entirely in your browser with no network calls, so it loads instantly, works offline once opened, and never sends your searches anywhere.
It is a handy companion whether you are learning HTTP, writing middleware, or chasing down why a response is not being cached.
FAQ
Are these every HTTP header that exists?
No. It focuses on the common standard headers you meet most often in web development. Custom and rarely used headers are not listed, but the examples show the standard formatting you can adapt.
What does the request/response/both label mean?
It shows where the header normally appears. "Request" headers are sent by the client, "response" headers by the server, and "both" headers like Cache-Control and Content-Type appear in either direction.
Can I copy a header straight into curl?
Yes. Each example is a complete "Header: value" line, so you can paste it after curl -H or into a fetch headers object and tweak the value.