How do I create a QR code for the CardDAV password of the sync.blue® app for Android?

Ing. Oliver Baltz

December 16, 2025 07:46 Updated

Purpose

Administrators can generate a QR code that contains a CardDAV password. This simplifies the manual setup of the sync.blue® app for Android when no MDM system is available. The QR code allows the password to be quickly copied to the clipboard using Google Lens and pasted into the app.

Why a QR code?

Fast access: No tedious typing of long passwords.
Error prevention: Reduces typos during manual entry.
Convenient: Ideal for BYOD scenarios or devices without MDM.

Step-by-step instructions

1. Create the QR code

QR code content: Password only (e.g. MYPASSWORD). Optional: Add an invisible character (zero-width space) and a line break to improve text recognition.

A) Creating a QR code with Python

import qrcode
payload = "\u200BMYPASSWORD\n"  # Invisible character + line break
img = qrcode.make(payload)
img.save("carddav_password.png")

B) Creating a QR code using an online service

Alternatively, such a QR code can also be created using any online service.

2. Provide the QR code

Print it or display it on a secure screen. Make it accessible to authorized persons only.

3. Copy the password using Google Lens

Open Google Lens on the Android device and point the camera at the QR code.
Tap the "magnifying glass" icon:
Copy the recognized password to the clipboard:

4. Paste the password into the sync.blue® app

Open the app and paste the copied password into the CardDAV credentials field.

Security notes

Never share the QR code publicly.
Delete it after use or store it securely.

Tip: A QR code can also be provided in the same way for the CardDAV API key (essentially the "username").