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