Derny — Privacy Policy

Last updated: July 2, 2026

Derny (“the app”, “we”) is an indoor cycling training app that connects to a Bluetooth smart trainer and heart-rate monitor and drives adaptive workouts based on your live metrics. This policy explains what data the app handles and why.

The short version: The app works fully without an account, and in that mode your data stays on your device. If you choose to sign in, your account email and your workouts and ride history are stored in our cloud so they sync across your devices. We do not sell your data, show ads, or track you across other apps or websites.

Information we handle

• Account information. If you choose to create an account or sign in (with Apple, Google, or email), we store your email address to identify your account. Signing in is optional.
• Workouts and ride data. The workouts you create and the rides you record — including metrics such as power, cadence, heart rate, duration, and timestamps. This is stored on your device, and synced to our cloud only when you are signed in.
• Bluetooth device data. The app reads live data from your smart trainer and heart-rate monitor over Bluetooth to display metrics and adjust workout targets. Your ride metrics are processed on your device and leave it only as part of a ride you save while signed in. (Separately, we send limited technical information about the trainer itself — see below.)
• Trainer diagnostic & compatibility data. When you are signed in and connect a smart trainer, we record limited technical information about that trainer — its advertised model, the control features it reports (such as ERG/power-target and resistance support) and their supported ranges, and whether the app was able to control it. We use this only to keep the app working reliably across the wide range of trainers our users own. It contains no health or ride data.
• Apple Health (optional, write-only). With your permission, the app saves your finished rides to Apple Health as indoor cycling workouts. The app does not read any data from Apple Health. Health data is managed by Apple on your device.
• Beta signup email. If you ask for a beta invite on our website, we store the email address you enter so we can send you your TestFlight invite and occasional beta updates, and so you can reply to us. We record whether you opened or clicked that email to gauge interest. You can unsubscribe at any time via the link in the email, and we will delete your address on request. We do not sell it or use it for advertising.

The app does not collect your location, contacts, photos, or advertising identifiers, and uses no third-party advertising or analytics/tracking SDKs.

How we use it

Data is used solely to provide and improve the app’s features: to store and sync your workouts and ride history, show your training metrics, (optionally) mirror finished rides to Apple Health, and keep the app working reliably across different smart trainers. We do not use your data for advertising, and we do not use it to track you across other companies’ apps or websites.

Where your data is stored

When you are signed in, your account and ride data are stored using Supabase, our cloud backend provider, which processes this data on our behalf. When you are signed out, your data stays only on your device.

Sharing

We do not sell your personal data and do not share it for advertising. We share data only with the service provider above, strictly to operate the app, and where required by law.

Your choices and data deletion

You can use the app without an account. If you have an account, you can request deletion of your account and associated cloud data by emailing us at the address below; we will delete it within a reasonable period. Workouts saved to Apple Health are controlled by you in the Apple Health app.

Security

Data in transit is protected with standard encryption (HTTPS/TLS), and cloud data is protected by access controls so each account can only reach its own records.

Children

Derny is not directed to children under 13, and we do not knowingly collect personal information from them.

Changes

We may update this policy as the app evolves. Material changes will be reflected here with a new “last updated” date.

Contact

Questions or requests: support@guayabagames.com.