There is only one file type that uses the .MUSE extension:
Adobe Muse Website Project
Website project file created by Adobe Muse, an easy-to-use Web development software that doesn't require knowledge of source code; stores a collection of pages ordered visually as a sitemap in the software; supports standard HTML elements as well as master page templates, freeform design elements, and many types of rich interactive content.
Adobe Muse sites can be previewed in the Muse software and published to the Web.
| Software's name | License | Platforms |
|---|---|---|
Adobe Muse CC — Discontinued |
Paid |   |
Updated: February 23, 2012