Frequency Book stores your frequency findings on your phones memory, not on server database. So this is your personal frequency logging and storing option. I have not yet implemented feature to backup database so be careful. I also can't promise that I don't change database structure in near future due this application is under development.
This application has been originally designed by Nitramite and it is listed among the Tools category. The app was downloaded and installed by over 1K users and its most recent stable release was on Mar 9, 2016. Users rated Frequency Book 4.5 on Google Play.