What is the difference between a request and a response header?

Request headers are sent by the client to give the server context (such as Accept or Authorization). Response headers are sent back by the server to describe the response (such as Content-Type or Cache-Control).

Which headers improve security?

Common security headers include Content-Security-Policy, Strict-Transport-Security, X-Content-Type-Options, X-Frame-Options, Referrer-Policy and Permissions-Policy.

Is any data sent anywhere?

No — this is a static reference that runs entirely in your browser. Nothing is uploaded.

HTTP Headers Reference

Searchable list of common HTTP request, response, security and CORS headers.

HTTP headers reference

A quick, searchable reference of the HTTP headers you meet most often, split into request, response, security and CORS groups. Each entry has a plain-English meaning and a real example value.

Type a header name or what it does — for example cache, cors or authorization — to filter the list. Everything runs in your browser.