# Expires header

> The absolute date and time after which a cached response is considered stale.

Source: https://apiguide.dev/headers/expires
Direction: response
Registered: yes
Defined in: RFC 9111, Section 5.3 <https://www.rfc-editor.org/rfc/rfc9111.html#section-5.3>
Updated: 2026-07-10

## What is the Expires header?

The `Expires` response header, defined in RFC 9111, contains an HTTP-date that marks when a response should no longer be considered fresh. After that moment, a cache must revalidate the resource before reusing it.

## API Usage & Best Practices

* **Superseded by Cache-Control**: When both `Expires` and `Cache-Control: max-age` are present, the relative `max-age` directive wins and `Expires` is ignored.
* **Invalid dates mean stale**: A malformed date, or the value `0`, is treated as already expired, forcing revalidation on the next request.

## Examples

```http
HTTP/1.1 200 OK
Expires: Thu, 09 Jul 2026 12:00:00 GMT
```