Last updated: April 18, 2026
These General Terms and Conditions (hereinafter "GTC") govern the contractual relationship between you (hereinafter "User") and
One Tree Hill GmbH
Oppenheimer Landstr. 70
60596 Frankfurt am Main
Managing Director: Werner Märkl
Commercial Register: HRB 81584, Local Court of Frankfurt am Main
VAT ID: DE217325183
Email: info@tennisflow.app
(hereinafter "Provider", "we", or "us")
regarding the use of the mobile application "TennisFlow" (hereinafter "App") and the corresponding website tennisflow.app (hereinafter "Website").
TennisFlow is an AI-powered app for analyzing tennis swings and movements. The App allows users to record videos of their play and have them evaluated using machine learning to receive technical feedback and suggestions for improvement.
These GTC apply to all versions of the App (free and paid versions) as well as all services offered via the App or Website. By registering, downloading, or using the App, the User accepts these GTC.
These GTC are directed at users residing in Germany, Austria, and Switzerland. Where deviating or supplementary provisions apply to individual countries, these will be separately indicated in the respective sections.
The use of TennisFlow requires the User to be at least 13 years old. Users under 18 years of age require the consent of a legal guardian for use and registration.
The use of TennisFlow is at the User's own risk. A prerequisite for use is that the User is in good general health. Specifically:
The analyses, tips, and workout recommendations provided by TennisFlow do not constitute medical advice and are not a substitute for a medical examination or sports physiotherapy treatment.
The extent of available features depends on whether the User uses the free version (FREE) or a paid version (PRO). The free version provides access to selected basic features. Advanced features are available via subscription (PRO).
The current prices and subscription models can be viewed in the Apple App Store and on the Website. The final price displayed to you in the Apple App Store at the time of purchase is always decisive. Prices shown on the Website are for general guidance only and may differ from the price displayed in the App Store for your country or region.
Whether sales tax or value-added tax (VAT) is included in the displayed price or shown or added separately depends on the tax rules of your country of residence and on how Apple presents prices. For users residing in Germany, Austria, and Switzerland, prices in the Apple App Store are generally displayed inclusive of applicable VAT.
Full use of TennisFlow may require additional equipment to be provided by the User at their own expense. This includes in particular:
This equipment is not part of the TennisFlow services and must be procured by the User at their own expense.
The use of TennisFlow requires the User to set up their smartphone near the tennis court – e.g., using a tripod, ball can with a rubber band, or another suitable mount. The User is solely responsible for ensuring that the setup is secure and stable.
⚠️ Warning: Ensure that the smartphone and mount are positioned in a way that neither you nor other players, spectators, or passersby can trip over them, run into them, or collide with them. Ensure that the setup is stable and the device cannot tip over or fall down.
The User acknowledges that setting up a smartphone, tripod, or other mount at the edge of the court may pose a risk of injury – especially from tripping, rolling an ankle, or colliding with or knocking over the equipment. The User bears full responsibility for safe positioning and is liable for damages and injuries resulting from improper setup.
The Provider is not liable for damage, loss, or destruction of the User's smartphone, tripod, mount, or other equipment occurring in connection with the use of TennisFlow. This specifically includes damages caused by:
TennisFlow uses artificial intelligence (including large language models such as Google Gemini) to generate technique analyses and workout recommendations. The User acknowledges:
⚠️ Warning: Only perform exercises and movements that match your fitness level and health condition. The Provider assumes no liability for injuries resulting from following AI-generated workout recommendations.
The User is solely responsible for ensuring that applicable legal regulations are observed when making video recordings on and around the tennis court. This specifically entails:
The User indemnifies the Provider against all third-party claims based on unlawful use of the video function or an infringement of personal rights, data protection rights, or other third-party rights by the User. The User also indemnifies the Provider against all third-party claims arising from the User breaching their obligations regarding the safe setup of equipment (§ 4.1, § 4.2) and resulting in injury or damage to third parties. The User assumes the reasonable costs of the Provider's legal defense, including all court and attorney fees at the statutory rate.
The video recordings remain exclusively on the User's device. No videos are transmitted to servers of the Provider or third parties. Further details can be found in our Privacy Policy.
The use of TennisFlow requires the creation of a user account. The User is obligated to provide truthful information and protect their account from unauthorized access.
When using the App for the first time, the User will be asked to read and accept these GTC as well as the Privacy Policy. Without acceptance, the use of the App is not possible.
For purchases via the Apple App Store or other platforms, the terms of the respective store provider also apply. The contract is generally concluded when the User confirms the purchase in the store.
The user agreement for the free version is concluded for an indefinite period. Paid subscriptions (PRO) have the minimum term displayed in the App Store and automatically renew for the same period unless canceled in advance.
Subscriptions purchased via the Apple App Store must be canceled via the App Store settings. The deadlines of the respective store provider apply. The free user account can be deleted at any time without giving reasons.
The right of both parties to terminate without notice for good cause remains unaffected. A good cause exists in particular if the User repeatedly or seriously violates these GTC.
Consumers generally have a statutory right of withdrawal. The exercise of the right of withdrawal depends on the distribution channel through which the contract was concluded:
a) For contracts concluded directly with us:
To exercise your right of withdrawal, you must inform us:
One Tree Hill GmbH
Oppenheimer Landstr. 70
60596 Frankfurt am Main
Germany
Email: info@tennisflow.app
by means of a clear declaration (e.g., via email or post) of your decision to withdraw from this contract. The withdrawal period is 14 days from the date the contract is concluded. To meet the deadline, it is sufficient for you to send your communication before the withdrawal period has expired.
b) For contracts concluded through a third-party provider (app store providers such as Apple, Google, etc.):
If you purchase subscriptions or in-app purchases through an app store provider, that provider is your contracting party for the financial transaction. In this case, the withdrawal must be declared directly to the respective app store provider and in accordance with its policies (e.g., through the support channels of the respective store). A withdrawal addressed to us cannot be processed or implemented by us for these purchases.
In the event of an effective withdrawal from a contract concluded directly with us, we will refund all payments received from you without undue delay, and at the latest within 14 days from the day on which the notification of withdrawal is received by us. For this repayment, we will use the same means of payment that you used for the original transaction.
For contracts and in-app purchases concluded through an app store provider, reversal and refund processing are carried out exclusively by the respective app store provider in accordance with its terms of use and deadlines.
The right of withdrawal expires for contracts concerning the supply of digital content (e.g., provision of premium features or software subscriptions) if we have begun to execute the contract after the User:
For purchases made through an app store provider, the terms and conditions of the respective store operator also apply to the early expiration of the right of withdrawal.
Swiss law does not provide for a statutory right of withdrawal in distance contracts for digital content. The above provisions on the statutory right of withdrawal (§§ 8.1–8.3) therefore primarily apply to users residing in the EU area (e.g., Germany or Austria). For purchases made through an app store provider, users in Switzerland are exclusively subject to the respective country-specific business and refund terms of the app store provider used.
The use of TennisFlow – including all analyses, workout suggestions, and recommendations provided by the App – is at the User's own risk.
For services provided free of charge, the Provider is liable – regardless of the legal grounds – exclusively for damages based on intent or gross negligence. Otherwise, liability is excluded.
For paid services, the Provider is liable:
Liability for damages resulting from injury to life, body, or health, which are based on a negligent or intentional breach of duty by the Provider, remains unaffected by the aforementioned limitations.
Subject to the provisions in paragraphs 9.3 and 9.4 and to the extent legally permissible, the Provider's liability for the following cases is excluded or limited to the foreseeable damage typical for this type of contract:
The Provider does not guarantee that using the App will lead to the sporting results aimed for by the User. Training results depend on individual factors (e.g., physical condition, training intensity, regularity) and can therefore vary widely among different users.
Claims under the applicable product liability regulations remain unaffected by the aforementioned liability limitations (Germany: Produkthaftungsgesetz – ProdHaftG; Austria: Produkthaftungsgesetz – PHG; Switzerland: Produktehaftpflichtgesetz – PrHG).
All contents provided in the App and on the Website (texts, graphics, logos, animations, software) are protected by copyright. The User receives a simple, non-transferable right of use for personal, non-commercial purposes. Reproduction, distribution, or public specific making available is not permitted without the prior written consent of the Provider.
The protection of your personal data is important to us. For details on the collection, processing, and use of your data, please refer to our Privacy Policy.
For users residing in the EU (Germany, Austria): The EU Commission provides a platform for out-of-court online dispute resolution: https://ec.europa.eu/consumers/odr/
We are neither obliged nor willing to participate in dispute settlement proceedings before a consumer arbitration board. Our email address can be found in the legal notice (Imprint).
For users residing in Switzerland: The EU platform for online dispute resolution does not apply. In the event of disputes, you can contact us directly: info@tennisflow.app.
The Provider reserves the right to change or adapt these GTC with effect for the future if this is necessary due to legal, regulatory, or technical developments and if the changes are reasonable for the User, taking the User's interests into account. The User will be informed via email or in-app notification at least two (2) weeks before the planned effective date of the new GTC. Changes will only become part of the contract if the User expressly agrees to them or if they are otherwise effectively incorporated in accordance with applicable law. If the User objects to the changes or does not give consent, the contractual relationship will continue under the previous terms; in this case, however, the Provider reserves the right to terminate the contractual relationship with ordinary notice at the next possible date (e.g., at the end of the current subscription period).
The law of the Federal Republic of Germany shall apply to the exclusion of the UN Convention on Contracts for the International Sale of Goods (CISG).
For consumers residing in the European Union (including Germany and Austria) and Switzerland, jurisdiction is governed by the statutory provisions (usually the consumer's place of residence). If the User has no general jurisdiction in Germany, Austria, Switzerland, or another EU/EFTA member state, or if they have moved their residence abroad after concluding the contract, the Provider's registered office (Frankfurt am Main) shall be the place of jurisdiction.
Should individual provisions of these GTC be or become invalid in whole or in part, the validity of the remaining provisions shall not be affected.
Note: You can view these GTC at any time on our website at tennisflow.app/en/termsg1. If you have any questions, please contact info@tennisflow.app.