DAVdroid is the only all-in-one synchronization solution for your contacts (CardDAV), calendars (CalDAV) and your tasks (based on VTODO).

The app is easy to set up and integrates perfectly with your favorite calendar/contacts app (including default apps). It can also be used seperately, if you either have CalDAV, CardDAV or only Tasks.
Compatible with almost every CalDAV/CardDAV servers and services, including Nextcloud, iCloud and Synology!
After installing, you can add a DAVdroid account from within the app. See for help. For more information, please see the FAQ and our forums
Key features:
⊛ Sync your DAV calendars (CalDAV) and address-books (CardDAV) and Tasks in a single app
⊛ Two-way synchronization (server ↔ client)
⊛ Native Android 4+ implementation
⊛ Flawless integration with your device and favorite apps
⊛ Easy setup (resource auto-detection, support for self-signed certificates)
⊛ Fast algorithms for high performance (CTag/ETag, limit sync time range for past events)
⊛ Optimized for phones and tablets
⊛ Super-secure and we respect your privacy!
⊛ DAVdroid is completely open source
Important compatibility notes
For all Android 4.1 and all Samsung usersThere's an Android bug that maybe causes accounts to be lost after a device reboot. To avoid this issue, please install the free app "DAVdroid JB Workaround". Samsung usersThe problem doesn't occur if you download DAVdroid using Samsung Store or Amazon Store.
On some Android 4.4.2 devices, DAVdroid accounts will disappear after an app update. If you experience this issue, please install the free app "DAVdroid JB Workaround". Details
AttentionDAVdroid must not be moved to the SD card! This will cause strange behaviour, including account and data loss.
Get the best out of this app …
⊛ … when using with your own DAV server (Radicale, DAViCal, SabreDAV, Baikal, …) and HTTPS – so you own and control all your data while having the comfort of synchronization between various devices. Or use a hosted DAV service you trust or the one of your company.
⊛ … and combine it with Evolution / Lightning / etc. on your laptop / PC
Why is it secure?
⊛ Source code is available (see homepage)
⊛ No need for giving your contacts/calendars to Facebook, Google, etc. Use your own server (or a trusted one)!
⊛ TLS is recommended to protected your communication so synchronization is secure even when using open Wi-Fi networks.
Successfully tested with:
⊛ AOL
⊛ Apple's Calendar and Contacts Server
⊛ Apple iCloud
⊛ Baïkal
⊛ Bitrix24
⊛ contactzilla
⊛ CozyCloud
⊛ DAViCal
⊛ eGroupware
⊛ fastmail
⊛ fruux
⊛ GMX
⊛ Group-Office
⊛ Horde
⊛ IceWarp
⊛ iCloud
⊛ Kerio Connect
⊛ KolabNow
⊛ Mac OS X Server
⊛ mailbox.org
⊛ mail.de
⊛ Nextcloud
⊛ openCRX
⊛ Oracle Communications UCS
⊛ OwnCloud
⊛ OwnCube
⊛ posteo.de
⊛ Radicale
⊛ SOGo
⊛ Synology DSM
⊛ Tine 2.0
⊛ web.de
⊛ Yahoo (calendars only)
⊛ Yandex
⊛ Zimbra Server