Nowadays we love to live the technical possibilities online services provide us with. But with getting used to the one or other solution or a specific cloud provider, the term of privacy is getting more and more important. Pushing everything into the „cloud“ (basically - other people’s computers) may be state of the art today. Even I - who tries to live the „cloud-first“-mantra - is constantly thinking of putting elementary data back into my own care.

This is nothing for the user that „just wants to work“, but solutions like Nextcloud help to turn away from public clouds, gathering your data at a place you can control. Together with a Messenger like Swiss-based Threema it is possible to put backups of your chats to your private cloud, a WebDAV-folder, - here - powered by Nextcloud. I want to guide you through this meaningful solution in just a few steps: You just need a WebDAV-accessible folder, Threema and just a few minutes of your time. Let’s go!

The Idea

During the journey from one to another messenger I discovered it to be pretty tough to motivate all other people around me to switch from a rather insecure messenger. Although the biggest known solution - WhatsApp - is still a mass phenomenon, it belongs to a company knowing to work with your data: Facebook. This doesn’t seem to mind many, many people especially as WhatsApp is free while you have to pay for Threema - one of the hurdles in our way. But this is another topic. Let’s assume you have convinced enough people around you to use a safe(r) messenger which complies to GDPR-rules and you want to backup the chats therein: Not in a public cloud, but in your own private, self controlled solution - enter, Nextcloud!


First of all, make sure you have met all the requirements to place the Threema Safe-backup on your Nextcloud-host as stated here. Define a folder where you want to put the backups - here it is Apps/Threema seen from the top of my Nextcloud-directory. Then put a new writeable folder named "backups" in there and add a simple text-file named "config" with the following content:

  "maxBackupBytes": 524288,
  "retentionDays": 180

The App

That's it from this side - now let's focus on the app. In my example I have used Threema on iOS so you my experience some optical differences when implementing this on Android. Finally, it shouldn't matter as the core idea behind is the same!

In Threema, switch to "My ID":

Then switch on "Threema Safe" and choose not to use Threema's backup storage but your own:

Then, enter a password which additionally secures your backup and verify this password. Second, enter your preferred WebDAV-Host (e. g. https://cloud.myinstallation.tld/remote.php/webdav/Apps/Threema) and (optional, but reasonable) your credentials for accessing your private Cloud. After confirming, the first backup is created according to the settings in the "config"-file:

So we have finally managed to use Threema Safe and our own private cloud for backing up our chats in a place we are in control of. As this seems to work, do not forget to convince your fellows to use rather a private cloud, a more private messenger or - ideally! - both!