Sorry to obfuscate, but is it an Apple product or an Android product? It makes a big difference.
If it is Android, the best I have found is FamilyGTG. It's basic but usable, and free. It also makes a difference as to whether you anticipate having internet access during your research. Libraries offer it, but cemeteries don't. If you have internet access a good idea is to upload your GEDcom file, which you can export from your current program, and upload it to any of the major family tree sites. You could mark it totally private.
Martin