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  1. HTTP (Hypertext Transfer Protocol)
  1. HTTP Headers
  1. Age
    1. Reading responses
    2. Writing responses
    3. Overview table
    4. Syntax
      1. Example
    5. History

Age

The Age header indicates the response was served from a cache without verification from the origin server; the value provides the number of seconds since the resource was updated with the origin server.

Reading responses

The value of the Age header is a non-negative integer. Implementations may wish to verify the value doesn't overflow the size of the number it's being read into during parsing.

Age was introduced in HTTP/1.1, and might not be implemented by old HTTP caches, or caches that refuse to honor the Age header.

Writing responses

For the conditions when a cache may serve a cached response, see Caching.

Overview table

Name
Age
Description
Indicates response was served from a cache.
Direction
Response
Specification
RFC 9111: HTTP Caching §5.1. Age

Syntax

Age = delta-seconds

Example

Age: 3550

Here, the resource was returned from a cache, and the entry was populated just under an hour ago (just under 3600 seconds).

History

  1. 1999-06: RFC 2616 §14.6. Age
  2. 2014-06: RFC 7234 §5.1. Age
  3. 2022-06: RFC 9111 §5.1. Age