Development builds are produced from the code of MuseScore that is being developed. They are intended for testers and advanced users who want to experiment with new features, or need access to the latest bug fixes and are willing to risk the instability of an unfinished product.
A file saved from a nightly build may not open in a future nightly or any released version. Use at your own risk.
Please report any bugs you find.
See also comparison of stable, prerelease, and development builds. Builds that have "master" in the name of the download package are based on the development branch that will eventually become MuseScore 3, with deep changes to the code structure, many new features, and high instability. Builds with "2.2" in the name are only slightly different from the current release of 2.1.