Expires header

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨July 2015⁩.

The HTTP Expires response header contains the date/time after which the response is considered expired in the context of HTTP caching.

The value 0 is used to represent a date in the past, indicating the resource has already expired.

Note: If there is a Cache-Control header with the max-age or s-maxage directive in the response, the Expires header is ignored.

Header type	Response header
Forbidden request header	No
CORS-safelisted response header	Yes

Syntax

http

Expires: <day-name>, <day> <month> <year> <hour>:<minute>:<second> GMT

<day-name>: One of Mon, Tue, Wed, Thu, Fri, Sat, or Sun (case-sensitive).
<day>: 2 digit day number, e.g., "04" or "23".
<month>: One of Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec (case sensitive).
<year>: 4 digit year number, e.g., "1990" or "2016".
<hour>: 2 digit hour number, e.g., "09" or "23".
<minute>: 2 digit minute number, e.g., "04" or "59".
<second>: 2 digit second number, e.g., "04" or "59".
GMT: Greenwich Mean Time. HTTP dates are always expressed in GMT, never in local time.