Depending on what you are looking for, you may be referring to one of these legitimate applications:
If you found a standalone file named exactly mff-0.5.apk on a random website or file-sharing network, please exercise extreme caution before attempting to install it: mff-0.5.apk
: An app with a 0.5 designation usually represents an unfinished, unstable prototype that could cause your phone to crash. 🛡️ How to Proceed Safely Depending on what you are looking for, you
: Always download your apps directly from the Google Play Store . mff-0.5.apk
Because "MFF" can stand for many different things and "0.5" looks like an incredibly early beta version number, downloading a file with this exact name from third-party sites carries high security risks.