DAVx is the only all-in-one app for all things CalDAV, CardDAV and WebDAV! It is a fully-featured sync 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. DAVx can also be used to access your remote WebDAV files.

Compatible with almost every CalDAV/CardDAV servers and services, including Nextcloud, iCloud and Synology!

Key features
• Sync your Calendars (CalDAV) and address-books (CardDAV) and Tasks (VTODO via CalDAV) in a single app
• Two-way synchronization (server ↔ client)
• Access your WebDAV files and work with remote storages — seamlessly just as they would be local on the device
• Flawless integration with your device and favorite apps
• Easy setup (resource auto-detection, support for self-signed certificates, authentication by client certificates)
• Fast algorithms for high performance (CTag/ETag, limit sync time range for past events, multi-threaded sync)
• Optimized for phones and tablets. Backward compatibility for old Android versions.
• Management options within the app (Create and Delete new calendars, address books and to-do lists*)
• Super-secure and we respect your privacy!
• Absolutely no ads and no tracking.
• GDPR compliant.
• DAVx is completely open source

* depends on server implementation / may be not supported by all servers

Important compatibility notes
Attention: DAVx 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 / Thunderbird / WebDAV storage etc. on your computer


Successfully tested with

• 1CRM
• A1.net
• all-inkl.com
• AOL Mail
• Baïkal
• Bitrix24
• Calendar and Contacts Server
• cPanel
• Cyrus IMAP
• DAViCal
• DavMail Gateway
• Daylite
• EDIS
• EGroupware
• Fastmail
• fruux
• GMX
• Google
• Group Office
• Hetzner KonsoleH
• Horde
• IceWarp
• iCloud
• Kerio Connect
• Kolab Now
• Kopano
• luckycloud
• macOS Server
• mail.de
• mail.ru
• mailbox.org
• Mailfence
• MDaemon
• Nextcloud
• openCRX
• Oracle Beehive
• Oracle Communications UCS
• ownCloud
• OwnCube
• Posteo
• Radicale
• SmarterMail
• SOGo
• Synology DSM
• Teambox
• Tine 2.0
• T-Online
• web.de
• Xandikos
• Yahoo Mail! (calendar only)
• Yandex
• Zimbra
• Zoho


... and many others:https://www.davx5.com/tested-with/

https://play.google.com/store/apps/details?id=at.bitfire.davdroid&hl=en