Heatsy

Terms of Use

Last updated: 9 October 2026

These terms apply to the Heatsy app for iPhone and the services behind it (“Heatsy”). Heatsy is made by DDDEV LTD, c/o Schoolgate Accounting Services, 46-50 Coombe Road, New Malden, London, KT3 4QF, England, company number 16374016 (“we”, “us”). Contact: support@heatsy.app.

By creating an account or using Heatsy you agree to these terms and to our Privacy Policy.

1. Licence and Apple’s EULA

Heatsy is licensed to you, not sold. Your use of the app is governed by Apple’s Licensed Application End User License Agreement (the “Standard EULA”, https://www.apple.com/legal/internet-services/itunes/dev/stdeula/) together with these terms. Where these terms add to the Standard EULA, both apply; where they conflict, the Standard EULA prevails for matters it covers, except for the open-licence material described in section 11.

Apple is not responsible for Heatsy or its content, and has no obligation to provide maintenance or support for it.

2. Account

You sign in with your email address and a one-time code. You must be at least 16 years old. Keep access to your email account secure: anyone who can read your email can sign in to Heatsy. Give accurate information about your training conditions, because your plan depends on it.

3. Subscription

Heatsy is available only with a paid subscription (Heatsy). There is no free tier.

  • Plans. A yearly plan, which may start with a free trial, and a monthly plan without a trial. The current prices, trial length and billing period are shown in the app and on the Apple payment sheet before you confirm. Prices are set in the App Store in your local currency and may include taxes.
  • Payment. Payment is charged to your Apple ID when you confirm the purchase, or, for a yearly plan with a free trial, when the trial ends.
  • Auto-renewal. Subscriptions renew automatically for the same period at the then-current price unless you cancel at least 24 hours before the end of the current period. Your Apple ID is charged within 24 hours before the period ends.
  • Free trial. If you cancel during the trial, you are not charged. Heatsy does not send a reminder before the trial ends, so note the date: the paywall and Profile show the price and the date of the first charge, and you can cancel any time before then. A trial is offered once per Apple ID, as Apple determines.
  • Cancel any time. Manage or cancel in Profile → Manage in App Store, or in your device’s Apple ID settings under Subscriptions. After cancelling, you keep access until the end of the period you have paid for or until the trial ends.
  • Refunds. Apple handles all payments and refunds. Request a refund at https://reportaproblem.apple.com. We cannot issue refunds for App Store purchases.
  • Without a subscription. When a trial or subscription ends, your workout log and body model stay readable, but plans, adaptation and other Pro features are locked until you subscribe again. Deleting the app or your account does not cancel a subscription.

4. Not medical advice

Heatsy is a training tool, not a medical device. It does not diagnose, treat, cure or prevent any disease or injury. The muscle heat map, plans, rep counts, energy estimates and all other content are for general fitness information only.

Strength training carries a risk of injury. Talk to a doctor before you start or change an exercise programme, especially if you are pregnant, have a medical condition, an injury, pain, or have not trained for a long time. Stop exercising and seek medical help if you feel pain, dizziness, shortness of breath or chest discomfort. You choose your weights and exercises and train at your own risk.

5. AI features

With your consent, some features use an AI model provided through third parties (see the Privacy Policy, “AI features”): choosing between suitable exercises when a plan is built, changing a plan from a short phrase, explaining adjustments after a workout and answering questions about exercises.

  • AI output can be incomplete or wrong. Our rules engine limits what the model can change, but always check a suggestion before you follow it, and use your own judgement about load and technique.
  • The AI features do not answer questions about pain, injuries, diagnoses, treatment or medication.
  • Do not enter information about other people, or health details beyond what the app asks for.
  • AI features are subject to fair-use daily limits. If the AI service is unavailable, the app falls back to plans and adjustments made by our rules.
  • You can refuse or withdraw consent at any time in Profile → Privacy & data and keep using Heatsy with rule-based plans.

6. Camera and Apple Health

Rep counting with the camera runs on your device and may miss or miscount reps. The energy figure saved to Apple Health is an estimate, not a measurement.

7. Acceptable use

You agree not to:

  • use Heatsy in breach of the law or of these terms;
  • attempt to access other users’ data or accounts, or our servers, beyond the features we provide;
  • interfere with, overload or probe the service, or bypass usage limits or the subscription;
  • use automated means to extract the exercise catalogue, content or AI features, or resell access to them;
  • submit content that is unlawful, abusive or infringes others’ rights;
  • reverse engineer the app except where the law allows it or where section 11 grants that right.

8. Your content

Your plans, workout log and notes remain yours. You give us permission to store, sync and process them only to provide Heatsy to you, as described in the Privacy Policy.

9. Our content

The app, its design, code, exercise catalogue, texts, animations and the Heatsy name and logo belong to DDDEV LTD or our licensors, except for the open-licence material in section 11.

10. Changes and availability

We may update Heatsy, add or remove features, and change these terms. If a change materially affects your subscription or your rights, we will tell you in the app before it takes effect. Continuing to use Heatsy after the change means you accept it. We aim to keep the service available but do not guarantee it will be uninterrupted or error-free.

11. Open-licence material

The 3D body model in Heatsy is adapted from Z-Anatomy and BodyParts3D and is licensed under Creative Commons Attribution-ShareAlike 4.0 (https://creativecommons.org/licenses/by-sa/4.0/). See Profile → About → Acknowledgements and https://github.com/heatsy-app/heatsy-body-model. Nothing in these terms or in the Standard EULA restricts the rights that licence grants you in the body model (the Z-Anatomy-derived geometry and per-vertex data). The head meshes combined with it in the app’s body files are a separate third-party asset and are not covered by that licence. The rest of the app is not covered by that licence.

12. Termination

You can stop using Heatsy and delete your account at any time in Profile → Delete account. We may suspend or close an account that seriously or repeatedly breaks these terms, after warning you where reasonable. If we stop offering Heatsy, we will give reasonable notice. Sections 4, 5, 9, 11, 13 and 14 survive termination.

13. Liability

Heatsy is provided “as is” and “as available”. To the extent the law allows, we are not liable for indirect or consequential loss, or for injury that results from exercise you choose to do. Our total liability to you is limited to the amount you paid for Heatsy in the 12 months before the claim. Nothing in these terms limits liability for death or personal injury caused by our negligence, for fraud, or any other liability that cannot be limited by law, and nothing affects your statutory rights as a consumer.

14. Governing law

These terms are governed by the laws of England and Wales. The courts of England and Wales have jurisdiction, but if you are a consumer you may also bring proceedings in the courts of the country where you live, and you keep the protection of the mandatory laws of that country.

15. Contact

DDDEV LTD, c/o Schoolgate Accounting Services, 46-50 Coombe Road, New Malden, London, KT3 4QF, England. Company number 16374016. Email: support@heatsy.app