Response

HTTP Vary Header

Determines how the response should be cached based on request headers. Ensures caches serve the correct version based on varying request criteria.

Purpose

Tells caches which request headers to consider when deciding whether to serve a cached response, enabling proper content negotiation.

Vary: * Vary: <header-name> Vary: <header-name>, <header-name> Example: Vary: Accept-Encoding Example: Vary: Accept-Language, User-Agent

See how to use the Vary header in different tools and languages.

curl -I https://api.example.com/resource
# Vary: Accept-Encoding
# This means the cached version depends on the Accept-Encoding header

Specifies caching directives for both requests and responses. Controls how and for how long content is cached by browsers and intermediate caches.

Indicates which content encoding (compression algorithm) the client supports. The server may compress the response body using one of these methods.

Indicates which natural languages the client prefers. The server uses this for content negotiation to return the appropriate language version.

Identifies the client software making the request. Contains information about the application, operating system, and version.

Test your APIs and inspect response headers in real-time

Complete reference of all HTTP request and response headers

vary headerhttp varyhttp headers guide