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CalDAV and CardDAV for Android with OX Sync

Notice about OX Sync App

The OX Sync App is no longer maintained by Open‑Xchange and will soon be removed from app stores. It will no longer be available for download and should no longer be used.

We have updated our articles on synchronization with OX Sync accordingly and recommend using modern alternatives such as DAVx⁵, Thunderbird, or other CalDAV/CardDAV‑compatible apps.

OX Sync​

The Android app "OX Sync" synchronizes calendars, tasks, and contacts between your mailbox.org account and your Android device. It uses the CalDAV protocol (for calendar data) and CardDAV protocol (for the contact data in your address books).

OX Sync is available for free download on the Google Play Store. After downloading, you only need to log in with your mailbox.org account credentials, and the app will automatically configure all necessary basic settings (Figure 1).

Figure 1: After logging in with your mailbox.org credentials, the basic settings will be automatically configured.

OX Tasks​

The task management is handled by the separate app "OX Tasks". By default, this is not linked on the home screen of your Android smartphone or tablet, but instead can be found in the list of all applications, from where you can place it on the home screen (Figure 2).

Figure 2: OX Mail, OX Drive, OX Sync, and OX Tasks on the home screen of an Android smartphone.

Alternative: DAVx⁵​

Many of our users already use DAVx⁵ successfully. This app is an open-source solution for synchronizing calendars (CalDAV) and contacts (CardDAV) with Android smartphones. It is fully compatible with mailbox.org and offers stable, background synchronization.

Why DAVx⁵?​

  • Reliable synchronization of calendars and contacts
  • Fully compatible with mailbox.org
  • Automatic background sync
  • Open Source (GPLv3) – Source code: github.com/bitfireAT/davx5-ose
  • Developed in Europe

Setting Up DAVx⁵​

Setting up DAVx⁵ is straightforward and takes just a few minutes:

1. Install DAVx⁵​

  1. Open the F-Droid Store or the Google Play Store.
  2. Search for “DAVx⁵” (or “DAVx5”).
  3. Tap on the app and install it.

Note: DAVx⁵ is paid in the Play Store – via F-Droid, the app is available for free.

2. Retrieve Connection Details from mailbox.org​

  1. Log in to mailbox.org in your web browser.
  2. Go to: Settings → Synchronization → CalDAV & CardDAV.
  3. There you will find your synchronization credentials.

Example server URL:
https://dav.mailbox.org

3. Add DAVx⁵ Account​

  1. Open DAVx⁵ and tap on “+” or “Add account”.

  2. Select Login with URL and username.

  3. Enter the following information:

    • Username: Your mailbox.org email address
    • Password: Your mailbox.org password or an app-specific password
    • Server URL: https://dav.mailbox.org

  4. Tap Next to verify the connection.

4. Select Calendars and Address Books​

  1. After successful connection, DAVx⁵ will list your available calendars and address books.
  2. Choose which ones to synchronize (e.g., “Personal Calendar”, “Contacts”).
  3. Confirm with Done or Synchronize.

5. Enable Synchronization​

  1. In DAVx⁵, open your account overview.
  2. Ensure that calendar and contact sync is enabled.
  3. Optional: Set how often to sync (e.g., every 30 minutes).

6. Use Calendar and Contacts Apps​

  1. The synchronized calendars will appear in your calendar app automatically.
  2. Contacts will be visible in your contacts app. You may need to activate the DAVx⁵ account there.

Setup Complete​

DAVx⁵ is now configured. Your calendar and contact data will be reliably synchronized between your Android device and mailbox.org.

Note: Synchronization occurs in the background according to your configured intervals. You can review and adjust sync settings anytime in the DAVx⁵ app.