DAVx⁵ is an open-source sync app for Android. It keeps calendars, address books and task lists in step with a server you choose, so names and appointments are not locked to one phone-maker account.
Last checked October 28, 2026.
At a glance
- What it is: An Android app that syncs calendars, contacts and tasks, and can open WebDAV files.1
- Works on: Android 7.0 or newer.7
- Price: Free on F-Droid, and free if you compile it. Commercial stores charge a small fee.1 The Play build also offers optional support badges.8
- Licence: GNU GPL version 3 only.7
- Best for: People who want phone calendars and contacts on a server they trust.
- Official site: davx5.com
What DAVx⁵ does (and how it protects your privacy)
DAVx⁵ is the bridge, not the diary. CalDAV is the usual standard for moving calendar entries between a server and a phone. CardDAV is the matching standard for contacts. DAVx⁵ speaks both, plus tasks. Calendars and contacts are written into Android’s calendar and contacts storage, which your other apps then show.3 It is not itself a calendar, contacts or tasks app, and it does not keep those entries on its own screens.3
The privacy gain is about place. bitfire web engineering, in Austria, says it never sees your contacts, events or tasks.28 Logins and synced copies stay on the phone and go only to the server address you entered.2 That can be a server you run. The Play listing names Nextcloud, iCloud and Synology among hosts it has tested.8
Other accounts are left alone. A contact stored under another account, or only on the phone, is not pulled into this sync.4 Choose the DAVx⁵ account when a new person or event should travel.3
DAVx⁵ key features
- Two-way calendars and address books: Address books, calendars and task lists can sync both ways.1
- Rich contacts: Names, phones, email, postal addresses, photos, notes and groups can sync.1
- Real calendars: Repeating events, exceptions, time zones and invitations, when the server supports them.1
- Tasks: Task lists sync with one companion app. The manual names jtx Board, OpenTasks and Tasks.org.5
- Files without a full copy: WebDAV folders can be opened and saved as if they were on the phone, including from other apps.1
- Your own certificates: Self-signed server certificates and client certificates are supported.1
- A tighter network: You can sync only on Wi-Fi, only on named Wi-Fi networks, or through a proxy you set.6
DAVx⁵ pros and cons
Pros
- Calendars and contacts show up in the apps you already open.3 A calendar such as Etar can be that screen.
- Other accounts on the phone are left untouched.4
- The app is free on F-Droid, and the source is published under the GPL.17
- The privacy policy says there are no ads and no tracking.2
- You choose which address books, calendars and task lists sync, including read-only ones.4
- Nextcloud, Fastmail and Google can use a provider login, so the account password is not sent on every request.3
Cons
- It is an Android app, and the current F-Droid build needs Android 7.0 or newer.7
- You still need a CalDAV or CardDAV server, plus apps to view contacts and events.3
- It is not a backup. A deletion on the phone is synced to the server as well.3
- The default past-event window is 90 days. Older events stay on the server but leave the phone calendar until you change that.6
- The Play listing says the app must not be moved to an SD card, or the account and data can be lost.8
- Background sync needs a battery-saving exemption. Huawei and Xiaomi phones may need extra steps so sync can run on its own.3
Is DAVx⁵ safe and private?
bitfire web engineering GmbH, in Bad Vöslau, Austria, develops DAVx⁵.8 F-Droid’s suggested version was 4.5.21-ose, added on 18 October 2026.7 The Play listing shows an update on 15 October 2026.8 F-Droid lists the licence as the GNU GPL version 3 only.7
The privacy policy says the developers do not extract usage data, show ads or track you.2 Google Play’s data-safety form, filled in by the developer, says no data is shared with third parties and that data is encrypted in transit.8 That protects the connection on the way. The server can still read the calendar. The same form says the app may collect location, files and docs, and two further types the summary does not name.8 Location permission is for an optional limit: sync only on named Wi-Fi networks. The policy says the app does not track location.2
Links from the app to the DAVx⁵ website add the package name and version, so the project can see which versions are in use. The policy says that is not personal data.2 A server address with no scheme gets https:// added, and plain HTTP is not recommended.4 You can distrust the phone’s built-in certificate authorities, or send traffic through a proxy, including a Tor proxy.6
If you sign in with a username and password, that password is sent to your server on every request.3 Prefer the provider login, or an app password made for this app, which you can cancel on its own.3 After sync, other apps with calendar or contacts permission can read the same stores.2
How to get started with DAVx⁵
- Install it from an official listing. Use the F-Droid package or the Google Play listing from bitfire web engineering.78
- Allow the permissions on the first screen. DAVx⁵ asks for contacts and calendar access. For sync while the phone is idle, accept the battery-saving exemption.3
- Add an account. Use the provider login for Nextcloud, Fastmail or Google when it is offered. Otherwise enter the base URL or email address, plus an app password if the host can make one.3
- Switch on what should sync. Enable the address books, calendars and task lists, then run Synchronize.3
- Save one test entry in the DAVx⁵ account. A phone-only contact or event will not leave the device.3
- Add tasks only if you need them. Install one tasks app, grant access, and select it. Only that app receives tasks.5
- Back up the server on its own. DAVx⁵ will sync a wipe as well as an edit.3 If you run the server, keep another copy. Duplicati is one way to schedule backups to a place you choose.
Who should use DAVx⁵ (and who might prefer something else)
DAVx⁵ fits when an Android phone should join a calendar server you trust. That can be a Nextcloud you run, or a host such as Fastmail that the Play listing says has been tested.8 The same listing includes iCloud, and the project site describes keeping an Android phone in step with an iPhone that uses iCloud.18 On a computer, the listing suggests Thunderbird.8 If that host also provides email, FairEmail can take the mailbox while DAVx⁵ takes the calendar and address book.
The account already on the phone may be enough if you are content with that provider. An iPhone cannot install DAVx⁵, which is an Android app.17 A restricted child profile cannot add accounts, so DAVx⁵ cannot run there.4
Frequently asked questions about DAVx⁵
Is DAVx⁵ free?
Yes on F-Droid, and yes if you compile the source. Commercial stores charge a small fee.1 Play’s update notes also describe badges you can buy to support the project.8
Is DAVx⁵ safe?
The privacy policy says your data stays on the phone and the server you set, with no ads and no tracking by the developers.2 Play’s form says data is encrypted in transit and not shared with third parties.8 The server, HTTPS, and other apps that can read the calendar still matter.42
Does DAVx⁵ work on iPhone?
No. It is Android-only, and current builds need Android 7.0 or newer.17 An iPhone can share the same server. iCloud is one service listed as tested.8
Does DAVx⁵ sync tasks?
Yes, as VTODO entries over CalDAV, into one tasks app. The manual names jtx Board, OpenTasks and Tasks.org.5 Notes and journals sync with jtx Board only, and only if the server supports them.5
