Privacy Policy

NKS Talk is a client for Nextcloud Talk. It connects to a Nextcloud server that you choose — your messages, attachments and conversations stay on that server. The app publisher runs no message storage and has no access to their content.

Your Nextcloud server

You enter the server address yourself. All communication happens between your phone and that server. How the data is handled there is up to its operator — if it is somebody else's server, their terms apply.

Sign-in credentials

Sign-in uses Login Flow v2, so you never type your account password into the app. The server issues a separate app password, which is stored in the phone's secure system storage — Android Keystore or Apple Keychain. It is never written to the conversation database.

Push notifications

So that notifications reach you while the app is not running, we operate our own notification proxy at nks-talk-notify.nks-hub.cz. It forwards notifications to Firebase Cloud Messaging (Android) or Apple Push Notification service (Apple).

• The proxy keeps your device identifier and the push provider token. It needs those to know where to deliver a notification.
• The proxy cannot read notification content. It is encrypted with your device's public key and only the private key stored on the phone can open it.
• On Android you can use Web Push via UnifiedPush instead of Firebase. Notifications then travel through the UnifiedPush distributor you choose.

Error reports and statistics

• Sentry — crashes and errors are sent to our own instance at sentry.nks-garage.cz (project nks-talk). Reports are redacted: the server address is shortened to https://<host> and authorization headers are replaced with <redacted>. Message content is never sent.
• Rybbit — anonymous usage statistics that tell us which parts of the app people use. They are not tied to an individual.

What the app does not do

• No advertising.
• No in-app purchases.
• No selling or sharing of data with third parties for marketing.

Deleting your data

Removing an account from the app unconditionally wipes the stored app password, the conversation data and downloaded attachments from the phone, and unregisters the device from the notification proxy. The app also tries to revoke the app password on the server itself; if that does not go through — because you are offline, for instance — the app tells you, and you can revoke it yourself in the Nextcloud web interface. Data on your Nextcloud server is untouched — that is your server administrator's domain.

Contact

Privacy questions go to dev@nks-hub.cz.

Last updated: 28 August 2026