Start with the data-flow question
Ask a concrete question: when you enter height and weight, does that measurement leave the device? A useful privacy policy names the fields and the destination. “Private” without a described data flow is branding, not an answer.
Massy calculates BMI on the device. Its height, weight, BMI result, category, reference range, unit preference, and check-in history remain in local app storage and are not sent to Massy, Google, RevenueCat, Apple, or advertisers. [1]
No account is not the same as no network activity
An app can operate without signup and still contact advertising, analytics, crash-reporting, purchase, or infrastructure services. The honest question is not only “Do I need an account?” but “Which systems receive which data, and why?”
The free version of Massy may request non-personalized ads from Google. Those requests do not contain measurements or BMI results. Google may still process technical advertising information such as IP address, device or app identifiers, ad interactions, diagnostics, and performance data depending on region and privacy choices. [1]
Does a no-account BMI tracker work offline?
Massy’s core BMI calculation and local check-in history do not need an account or cloud profile. Your saved measurements remain available from the app’s local storage on that device. [1]
That does not mean every app feature is permanently offline. Advertising, regional privacy controls, and purchase or restore flows may contact Google, RevenueCat, or Apple. “Local measurements” is the accurate claim; “the whole app never uses a network” is not. [1]
Check purchases separately
If an app offers a purchase, payment and entitlement services need enough information to process or restore it. That does not require giving them health measurements, but the separation should be explicit.
Massy’s optional one-time Remove Ads purchase is processed by Apple and verified with RevenueCat. Purchase status and transaction information are separate from the locally stored measurements; Massy does not receive payment-card details. [1]
Understand deletion and backups
Local storage should come with a clear deletion story. Check whether individual entries can be removed, whether deleting the app clears its local database, and whether operating-system backups may retain a recoverable copy outside the app’s control.
Massy has no cloud profile for its team to delete. Removing the app clears its local app data, subject to backups controlled by the device operating system. That limitation is stated instead of promising deletion from systems the app does not control. [1]
A five-question privacy checklist
Before using any BMI or weight tracker, look for direct answers to these questions.
Do my height, weight, result, or history leave the device?
Is an account or cloud profile created?
Which ad, analytics, crash, or purchase services receive technical data?
Can I use the core calculator without granting tracking permission?
How do I remove saved data, and what happens to device backups?
Sources
- Massy privacy policyMassy