Effective: November 10, 2026
These terms cover your use of the Derny app (iPhone and Android), the derny.app website, and the Derny connector that lets Claude or ChatGPT manage your workouts. By using Derny you agree to them. If you don’t agree, please don’t use it.
The short version: Derny is a beta. It can break. You ride at your own risk, and treadmills and other powered machines can move under you, so stay in control of the machine and stop whenever you need to. Derny is not medical advice. Workouts you or your AI write are yours. Be decent, don’t abuse the service, and you can delete your account at any time.
Derny is operated by Guayaba Games LLC, a Michigan limited liability company (“we”, “us”). You can reach us at [email protected].
You can use much of the app without an account. To sync workouts across devices, or to connect an AI assistant, you sign in with Apple, Google or email. Give us a real email address, keep your sign-in secure, and tell us if you think someone else has got into your account. You are responsible for what happens under your account. You must be at least 13 years old to use Derny.
Don’t use Derny to break the law, to attack or overload our servers, to probe for weaknesses without asking us first, to scrape the service, or to get around limits or safety features such as the heart-rate hold or a treadmill’s max auto speed. Don’t use the connector to send us anything harmful or abusive. We may limit or suspend access that does any of this.
The workouts you create in Derny are yours, including workouts an AI assistant writes for you through the connector. You give us permission to store, sync and process them so the app works, and, as the privacy policy explains, to use the ride data shared during the beta to improve Derny. Don’t add content you have no right to use. We may remove content that breaks these terms.
The connector lets an AI assistant you choose (Claude or ChatGPT) create, list, read, edit and delete the workouts in your Derny library, and send us feedback. You approve it with a Derny sign-in, and you can disconnect it at any time in Settings → Connected Apps. The assistant cannot see your recorded rides and cannot control your trainer, treadmill or elliptical.
AI assistants make mistakes. A workout an AI writes can be too hard, too long or just wrong, and an assistant with access can also change or delete workouts in your library. You are responsible for checking a workout before you ride it and for what you choose to ride. Your use of Claude or ChatGPT is covered by their terms, not ours.
Exercise is risky, and indoor machines add their own risks. Treadmills have a moving belt, and trainers and ellipticals can change resistance. Derny adjusts targets, or tells you what to set, based on the signals your machine and heart-rate monitor send. Those signals can be late, wrong or missing. You are responsible for your own safety: check your machine and your surroundings, use any safety key or stop button, set a max auto speed you are comfortable with, and stop if something feels wrong.
Derny is not a medical device and does not give medical advice. Heart-rate targets are estimates. Talk to a doctor before you start a hard training program, especially if you have a heart condition or any other health concern. Exercise at your own risk.
Derny is in beta. It is provided “as is” and “as available”, with no promise that it will be accurate, uninterrupted, error-free or compatible with your equipment, and features may change or disappear. To the fullest extent the law allows, we disclaim all warranties, express or implied.
To the fullest extent the law allows, we are not liable for indirect, incidental, special or consequential damages, or for lost data, lost profits, or injury or damage arising from your use of Derny, your equipment, or a workout, whether it was written by you, by us or by an AI assistant. Our total liability to you for any claim related to Derny is limited to the amount you paid us for it in the past 12 months, which is zero while Derny is free. Some places don’t allow these limits, so they apply only as far as your local law permits. Nothing here limits liability that cannot be limited by law.
Derny works alongside services we don’t run, including Apple Health, Health Connect, Strava, Claude, ChatGPT, and your own machines and sensors. Each has its own terms and privacy policy, and we are not responsible for them. If you connect one, you are agreeing to its terms with the provider.
You can stop using Derny at any time and delete your account and data from inside the app. The steps are on our account deletion page, and the privacy policy explains what is deleted and what is kept without your name. We may suspend or end your access if you break these terms or if we have to stop running Derny. The sections on liability, content and governing law continue after that.
We may update these terms as Derny changes. Material changes will be posted here with a new date. If you keep using Derny after a change, you accept the new terms.
These terms are governed by the laws of the State of Michigan, USA, without regard to its conflict-of-law rules. Any dispute will be heard in the state or federal courts located in Michigan, and you and we agree to those courts’ jurisdiction, except where the law where you live gives you the right to bring a claim in your local courts.
Questions about these terms: [email protected]. See also our privacy policy.