Terms of Service

Effective date: 2026-04-20

By downloading, installing, or using Chronosync Plus ("the app"), you agree to these Terms of Service. If you don't agree, please don't use the app.

1. The service

Chronosync Plus is a self-tracking application for observing and reasoning about your circadian rhythm, vitamin-D exposure, and screen-time habits. The app runs entirely on your device. There is no server-side account and no server-stored data.

2. Not medical advice

Chronosync Plus is not a medical device, diagnostic tool, or substitute for professional medical advice. Vitamin D IU estimates, burn-risk timings, circadian phase readings, and coaching suggestions are general physiological approximations based on public models (SunCalc for solar positions, the Fitzpatrick MED table for skin erythema thresholds, etc.). They are not clinical measurements.

Do not rely on Chronosync Plus to decide whether to take, continue, adjust, or stop any medication, supplement, or therapy. Do not rely on it to determine safe sun exposure — our burn-time estimates can be off by tens of minutes depending on altitude, reflective surfaces, and individual skin variation we cannot measure. If you have questions about sleep, light exposure, or vitamin D status, consult a qualified clinician.

3. Age restriction

Chronosync Plus is intended for adults aged 18 and over. We do not knowingly permit use by children under 13. Parents and legal guardians are responsible for supervising any use by minors under their care.

4. Your account and data

You are responsible for the password you set on the app. Because your local store is encrypted with a key derived from that password, we cannot recover it if you forget it. Export your data periodically (Settings → Export) and store the file somewhere safe if you want a recovery path.

See the Privacy Policy for details on what we store, encrypt, and transmit.

5. Acceptable use

You agree not to:

Reverse-engineer, decompile, or modify the app except as permitted by law;
Use the app to harass, surveil, or collect data about another person without their consent;
Redistribute the app or its assets commercially without permission;
Attempt to exploit bugs or vulnerabilities in ways that harm other users, our infrastructure, or the third-party APIs we depend on.

6. Third-party services

The app makes network calls to Open-Meteo, OpenStreetMap Nominatim, and timeapi.io. Your use of those services is subject to their own terms, linked from the Privacy Policy. We are not responsible for the availability, accuracy, or behavior of third-party services.

7. Disclaimers

The app is provided "as is" and "as available", without warranties of any kind, express or implied — including but not limited to merchantability, fitness for a particular purpose, non-infringement, or accuracy. We do not guarantee the app will be uninterrupted, error-free, or free of harmful components.

8. Limitation of liability

To the fullest extent permitted by law, we shall not be liable for any indirect, incidental, special, consequential, or punitive damages — including loss of profits, data, goodwill, or other intangible losses — arising out of or relating to your use of the app, even if we have been advised of the possibility of such damages.

9. Termination

You can stop using the app at any time by uninstalling it. We may terminate or suspend access to new versions of the app at any time, for any reason, without notice. Existing installed copies will continue to function locally.

10. Changes to these terms

We may update these terms. Material changes will be communicated via the in-app "What's new" panel and reflected in the effective date above. Continued use after an update constitutes acceptance.

11. Contact

Questions about these terms: support@chronosyncplus.com