| [Simple Contacts](https://github.com/SimpleMobileTools/Simple-Contacts) [![F-Droid](https://img.shields.io/f-droid/v/com.simplemobiletools.contacts.pro?style=flat-square)](https://f-droid.org/en/packages/com.simplemobiletools.contacts.pro/) | | Open-source. Part of the [Simple Mobile Tools](https://github.com/SimpleMobileTools) project. |
| [EteSync](https://www.etesync.com) [![F-Droid](https://img.shields.io/f-droid/v/com.etesync.syncadapter?style=flat-square)](https://f-droid.org/en/packages/com.etesync.syncadapter/) | | Secure, end-to-end encrypted, and open-source sync for your contacts, calendars and tasks. |