The webapp which I will produce in my master thesis will be usable on a smartphone. It works offline, too. It won’t have personal task management stuff like start dates, but when there is a demand, I could code it.
This app was created by me and a fellow student at university. It is working nice, but I don’t like its progamming language (Java is so cumbersome compared to Python). Therefore I will not develop it any further. If you want to pick it up, I can explain you some code, but in general it should be written cleanly.
Download the .apk file. If you have a Google Play Developer Account, feel free to publish the app.
Synchronisation with a JSON file in your OwnCloud is possible. However, Desktop TreeNote is not able to synchronize with a JSON file. When I finished my master thesis I will have a neat tree API, someone may implement it to the Android app to have fluent synchronisation.
The code is on GitHub.