max-age cache directive
Response max-age defines a freshness lifetime in seconds from response generation.
- caching
- directives
- freshness
Response meaning
In a response, max-age=N says the response is stale after its age exceeds N
seconds. Age is calculated from response generation and time resident in upstream
caches, not from when the current client first saw it.
Cache-Control: max-age=300
Age: 120
Expected result: absent other constraints, the stored response has about 180 seconds of freshness remaining at this observation.
Request meaning
In a request, max-age limits the age of a response the client is willing to accept. It does not force an origin to generate a new representation.
Precedence
For a shared cache, s-maxage overrides max-age. Max-age overrides Expires for
the same response. Invalid repeated values can make freshness handling
conservative.