MJD Convert for Android
Automatically provides the MJD of the current date, and can convert between any MJD and date in either direction. Also gives the day number in the current year. Note that months are in English; not as on the screenshots! Simple, clear, no frills; just exactly the information you want.
by Q####:
The app is great, works both ways (MJD to date and date to MJD) only one thing, I wish it could also do time and not only date. (Like 51663.3627)