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Caching

Expires

Specifies a date/time after which the response is considered stale. Superseded by Cache-Control max-age.

Syntax

Expires: <http-date>

Example

Expires: Thu, 12 Mar 2027 10:00:00 GMT

Description

Expires specifies an absolute date after which the response is stale. Original HTTP/1.0 caching mechanism.

When both Cache-Control: max-age and Expires are present, Cache-Control takes precedence.

Limitation: requires synchronized clocks. Cache-Control: max-age (relative time) is preferred.

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Related Headers

Age
Indicates how long a response has been stored in a cache, in seconds since generation.
Cache-Control
The primary header for controlling caching behavior, defining how and for how long responses can be cached.
Pragma
Legacy HTTP/1.0 header for backward-compatible cache control. Replaced by Cache-Control.
Vary
Tells caches which request headers to consider when deciding whether to serve a cached response.

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