Secure, end-to-end encrypted, and privacy respecting sync for your contacts, calendars and tasks (Android client).
Please see the EteSync website for more information.
EteSync is licensed under the GPLv3 License.
EteSync's source code was originally based on DAVdroid but the codebases has since diverged quite significantly.
This project relies on many great third party libraries. Please take a look at the app's about menu for more information about them and their licenses.