If you live and breathe Android, then you’re either going to have to accept that you will be sending personal data to Google to enjoy all of Google’s apps and services. Or you can just totally skip Google Play Services and live on the fringes of the Android ecosystem. There’s one way to get around sending your data to Google, and that is have your own secure data server, or use a trusted cloud-based data server. That is where the DAVdroid app comes in.
Made by Bitfire Web Engeneering, DAVdroid is an app you can install on your Android device to make syncing your data from your server to your device just a bit more convenient. The app works best if either you use your own DAV server (Radicale, DAViCal, SabreDAV, Baikal, etc.), or you use a cloud-based DAV service like Owncloud or Nextcloud, or if your company has set up one for your specific use.
DAVdroid is made to play nice with a lot of platforms, including Apple’s iCloud, Owncloud, Nextcloud, Yahoo calendars, Radicale, AOL, Horde, IceWarp, and a lot of other names in cloud-based data. And with the current update to app version 1.3, DAVdroid now features certificate management for trusted certificates and connection security.
The DAVdroid app is available for USD$3.00 via the Google Play Store, but it is also completely open source. You can actually go to their gitlab page to view the source code, and if you want, compile it by yourself and use the app for free.