Since the begining of the service, we support the uncompressed MusicXML format, used by more than 150 softwares.
From now on, we support its compressed version, which use the *.mxl file extension. The support of this format allows you to import your files from any music software editor. Just click on "Import an existing score" in your dashboard.
Any question, comment or idea? Feel free to drop us an email at team@flat.io.