FYI: aCalendar+ does this, using OpenTasks storage backend. (Not open source though.)
List of supported task applications
A list of supported tasks application would help.
Until know, I found these two applications:
- I use it on a daily base
- Unfortunately, it does not support categories
- Not supported anymore
I’m searching for a tasks application which supports categories.
At the moment, only OpenTasks is supported by DAVdroid.
I guess it will be hard to find a tasks application which supports categories and then integrate its API into DAVdroid (but if it uses an API similar like OpenTasks, it won’t be too hard).
Maybe you can send a patch for category support to OpenTasks?