Translation for your convenience — the German version is the binding one.
This policy describes what data the Zählwerk app for iPhone, iPad and Android devices processes. (The website has its own policy; alongside it you find the terms of use and the provider details in the legal notice.)
The short version
- Your meter data stays on your device. There is no account and no Zählwerk server storing your meters, readings or photos.
- Only when you have a meter photo read by cloud recognition is that single photo sent to our recognition service — read there and then discarded.
- Purchase and subscription run through the App Store or Google Play. Payment data never reaches us.
- No ads, no tracking, no analytics services.
Controller
Stefan Dolfen, Kurt-Stöbe-Str. 45, 50181 Bedburg, Germany
E-mail: hello@zaehlwerk.app
Data in the app — on your device only
Meters, readings, receipt photos, tariffs, addresses and settings are stored exclusively locally in the app on your device. We have no access to them. On request a biometric lock (Face ID / Touch ID / fingerprint) protects access. You delete this data yourself — in the app or by uninstalling.
Photo recognition (Zählwerk recognition)
By default the built-in Zählwerk recognition reads your meter photos. It only becomes active when you take or pick a photo yourself — never in the background. The following is transmitted:
- the meter photo,
- optionally the last known reading of the selected meter (as a recognition hint),
- a randomly generated device identifier (for the daily limit and abuse protection). It contains no information about you or your device.
- an indication of whether the request counts against the trial or a subscription, and while a subscription is running a pseudonymous licence identifier — both are explained in the section Purchase, trial and subscription.
Processing runs via our service api.zaehlwerk.app (hosted on Google Cloud) and uses Google's AI image models (Vertex AI). The image analysis may take place on servers outside the EU; the standard data protection mechanisms of the Google Cloud platform apply (data processing terms, EU standard contractual clauses).
The photo is discarded after analysis. It is neither used by us nor — under Google Cloud's contractual terms — to train AI models. On our side we only keep technical metadata without the photo (time, duration, outcome status, truncated hash of the device identifier and, while a subscription is running, the licence identifier) — for the daily limit, the trial photo counter, operations monitoring and abuse protection, for as long as required for that. If you save a reading recognised from a photo, the app also reports back whether the recognised value was accepted or corrected — only as a class (yes/no and the kind of deviation, such as “decimal point shifted”), never the reading, the meter number or the photo. This is how we measure recognition quality; the report is omitted if you use your own recognition service or have switched cloud recognition off.
Legal bases: Art. 6(1)(b) GDPR (provision of the feature you requested) and Art. 6(1)(f) GDPR (abuse protection and operational security).
Cloud recognition can be switched off at any time under Settings → Cloud recognition — the app then analyses photos on the device only, and nothing is transmitted.
Purchase, trial and subscription
You buy Zählwerk once; cloud recognition is a monthly subscription. Purchase and subscription run through the App Store or Google Play — card numbers, billing addresses and other payment data never reach us. To know what is unlocked, the app asks the store which purchases and subscriptions belong to your account; that query stays between your device and the store, no Zählwerk server is involved. What the store records is governed by its own privacy policy. (What the trial, purchase and subscription cover is described in the terms of use.)
The start of the trial is stored on your device — in the keychain on iPhone and iPad — and does not leave it.
If you use Zählwerk recognition in the cloud, one additional piece of information is sent with each request:
- During the trial our service counts the 50 trial photos per device identifier. For that, the app only tells it whether the request counts against the trial or against a subscription — no reading, meter number or photo is contained in it.
- While a subscription is running, a pseudonymous licence identifier is sent alongside the device identifier: a 16-character digest calculated with SHA-256 from the transaction number of your store purchase. It serves to count the devices of one subscription and to detect abuse. The digest cannot be traced back to you, your store account or your payment data, and the transaction number itself never leaves your device. The identifier is kept and deleted like the device identifier (monthly statistics).
Without a subscription after the trial, no cloud request is made at all — the app then does not contact the service. On-device recognition, manual entry and your own access (see below) remain free in any case.
Legal bases: Art. 6(1)(b) GDPR (provision of the purchased feature) and Art. 6(1)(f) GDPR (abuse protection and operational security).
Your own AI provider (optional)
Instead of Zählwerk recognition you can store your own access to Google Gemini, Mistral or OpenAI, or use your own Ollama server in your home network. The photo then goes directly from your device to the chosen provider; that provider's privacy policy applies. Your API key is stored exclusively in the keychain or encrypted storage of your device and never reaches a Zählwerk server.
Easee wallbox (optional)
If you connect your Easee wallbox, the app fetches your charging data directly from Easee; Easee's privacy policy applies. Your Easee credentials are kept only in the keychain or encrypted storage of your device. No Zählwerk server is involved.
Location (optional)
In the setup assistant you can have your address suggested on tap. For that, your location is determined once and passed to your platform's service (Apple or Google) for address lookup. The location is not stored and does not go to any Zählwerk server.
Cloud backup & device sync (optional)
On request the app saves a copy of your data (including photos) to your own cloud storage — your iCloud Drive or a folder you choose (e.g. Nextcloud or Dropbox). Only your cloud provider has access to this backup under its own terms, Zählwerk does not. Syncing several devices runs exclusively through this folder; there is no intermediate station.
Notifications
The monthly reading reminder is scheduled locally on your device. There is no push server.
What the app does not do
No ads, no tracking, no third-party analytics or statistics services, no selling or sharing of data beyond what is described above.
Your rights
You have the right to access, rectification, erasure, restriction of processing, data portability and objection, and the right to complain to a data protection supervisory authority. Since your meter data never reaches Zählwerk, in practice this only concerns the technical metadata of photo recognition (device identifier and, while a subscription is running, the licence identifier) — write to hello@zaehlwerk.app for that.
Last updated: 13 September 2026. If the app changes, we update this policy and publish it here.