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Access-Control-Max-Age header

files/en-us/web/http/reference/headers/access-control-max-age/index.md

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The HTTP Access-Control-Max-Age {{Glossary("response header")}} indicates how long the results of a {{glossary("preflight request")}} (that is, the information contained in the {{HTTPHeader("Access-Control-Allow-Methods")}} and {{HTTPHeader("Access-Control-Allow-Headers")}} headers) can be cached.

<table class="properties"> <tbody> <tr> <th scope="row">Header type</th> <td>{{Glossary("Response header")}}</td> </tr> </tbody> </table>

Syntax

http
Access-Control-Max-Age: <delta-seconds>

Directives

  • <delta-seconds>
    • : Maximum number of seconds for which the results can be cached as an unsigned non-negative integer. Firefox caps this at 24 hours (86400 seconds). Chromium (prior to v76) caps at 10 minutes (600 seconds). Chromium (starting in v76) caps at 2 hours (7200 seconds). The default value is 5 seconds.

Examples

Cache results of a preflight request for 10 minutes:

http
Access-Control-Max-Age: 600

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

  • {{HTTPHeader("Access-Control-Allow-Headers")}}
  • {{HTTPHeader("Access-Control-Allow-Methods")}}