application/mp21 is a application media type commonly associated with .m21, .mp21 extensions.
Quick facts
What is application/mp21
application/mp21 is one of the application media types used on the internet. When serving this content over HTTP, set the Content-Type header in the response, for example:
Content-Type: application/mp21
Related entities: associated extensions include .m21、.mp21, and is delivered over HTTP via the Content-Type header, commonly with GET, POST, PUT and PATCH requests.
Related formats:
Relation chain
Related extensions
Related MIME types
Used with
Related headers
Related methods
Frequently asked questions
application/mp21 is a application media type used to identify a content format; servers announce it to clients with the Content-Type header.
Extensions such as .m21, .mp21 are associated with this MIME type.
Send Content-Type: application/mp21 in the HTTP response.
Sources & standards
Updated 2026-08-18
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