HTTP Header Reference
Search common HTTP headers and see what they are usually used for.
Look up any HTTP header
HTTP headers control caching, security, content type, and more, and it is hard to remember what each one does. This searchable reference explains common request and response headers in plain language, so you can confirm a header’s purpose in seconds.
It complements a header parser: when you spot an unfamiliar header in a response, look it up here to understand what it is doing. Search by name or keyword and get a concise explanation of what the header controls and when to use it.
Look it up, locally
Each entry explains what the header controls — caching, security, content type — so you can set it with confidence. The reference runs entirely in your browser.
Frequently asked questions
Which headers does it cover?
Common request, response, caching, and security headers, such as Cache-Control, Content-Type, Authorization, ETag, and Set-Cookie, each with a plain-language explanation.
How do I see the headers a site sends?
In Chrome, open DevTools, go to the Network tab, click a request, and look under Headers.
Are header names case-sensitive?
No. HTTP header names are case-insensitive, and HTTP/2 sends them in lowercase.
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