Terms of Use

Last updated: 6 October 2026

These Terms of Use ("Terms") are a legal agreement between you and Leon Johnstone ("we", "us", "our"), the developer of the Callus mobile application (the "App"). They govern your use of the App, its coaching features, and any related services, content, updates and supplements we provide (together, the "Service").

By downloading, installing or using the App, you agree to these Terms. If you do not agree, do not use the App.

1. Who these Terms are with, and Apple's role

1. These Terms are concluded between you and us only, and not with Apple Inc. ("Apple"). We, not Apple, are solely responsible for the App and its content.
2. If there is any conflict between these Terms and the Apple Media Services Terms and Conditions (the "Usage Rules"), the Usage Rules apply to the extent of that conflict. These Terms may not provide for usage rules that conflict with the Apple Media Services Terms and Conditions as of the date you accept them.
3. Apple has no obligation whatsoever to provide any maintenance or support services for the App. Maintenance and support are our responsibility, to the extent described in these Terms or required by applicable law.

2. Eligibility

You must be at least 16 years old to use the App. If you are under 18, or under the age of majority where you live, you may use the App only with the involvement and permission of a parent or legal guardian, who agrees to these Terms on your behalf and is responsible for your use of the App. The App is not directed to children under 13.

3. Health and safety

3.1 Not medical advice

The App provides general information about exercise technique. It does not provide medical, physiotherapy, rehabilitation, nutritional or other healthcare advice, diagnosis or treatment, and it is not a substitute for a qualified professional. Nothing in the App creates a doctor–patient, therapist–patient or similar professional relationship. If you have, or think you may have, an injury, a medical condition, pain, a heart condition, are pregnant or have recently given birth, or have any other health concern, consult a qualified healthcare professional before starting or changing any exercise, and follow their advice over anything in the App.

3.2 The coaching is generated by AI, and it can be wrong

Coaching in the App is generated by artificial intelligence from still frames extracted from your video, pose and depth estimates made on your device, and information you provide. It can only assess what is visible in the frames it receives. It may misidentify a movement, a body part or a person; miss faults; describe faults that are not there; or give guidance that is unsuitable for you. Measurements such as joint angles are estimates. Use your own judgement about every cue, drill, regression or suggestion, and do not follow anything that seems unsafe or inappropriate for you.

3.3 Your responsibility for your own training

Exercise carries an inherent risk of injury, and in rare cases serious injury or death. You choose whether, when, where and how to perform any movement, and you do so voluntarily and at your own risk. In particular, you are responsible for:

• training within your own ability, fitness and experience, and choosing appropriate loads;
• warming up, using suitable equipment in good condition, and using spotters, safety bars or supervision where appropriate;
• making sure the space around you is safe, including for other people, and that you are permitted to train and film there;
• telling the coach about any injury, pain or limitation, while understanding that it cannot examine you; and
• stopping immediately, and seeking help where appropriate, if you feel pain, dizziness, faintness, shortness of breath or any other warning sign.

3.4 Filming safely

Do not let filming distract you from training safely. Position your device so that it cannot fall, obstruct you or others, or create a hazard.

4. Licence to use the App

1. Scope. We grant you a limited, non-exclusive, non-transferable, revocable licence to use the App for your personal, non-commercial purposes on Apple-branded products that you own or control, as permitted by the Usage Rules. This includes use by other accounts associated with you through Family Sharing or volume purchasing, where the Usage Rules allow it.
2. Restrictions. Except as expressly permitted by these Terms or by applicable law that cannot be excluded, you may not: (i) distribute, make the App available over a network where it could be used by multiple devices at the same time, rent, lease, lend, sell, redistribute or sublicense the App; (ii) copy, decompile, reverse-engineer, disassemble, attempt to derive the source code of, modify, or create derivative works of the App, any updates, or any part of it (except where, and only to the extent that, a restriction is prohibited by applicable law or by the licensing terms of open-source components included in the App); or (iii) remove, alter or obscure any proprietary notice.
3. Updates. These Terms govern any updates we provide that replace or supplement the original App, unless an update comes with separate terms, in which case those terms apply.
4. Ownership. The App and the Service, including their software, design, text, graphics and coaching materials (but excluding Your Content, defined below), are owned by us or our licensors and are licensed, not sold, to you. All rights not expressly granted to you are reserved.
5. Breach. If you breach these restrictions, you may be subject to legal action and liability for damages.

5. Your content

1. What counts as Your Content. "Your Content" means videos you record or select, still frames and data derived from them, the text you write, and the information you give the coach.
2. You keep ownership. You retain all rights you have in Your Content.
3. Permission to provide the Service. You grant us, and the service providers acting on our behalf, a worldwide, non-exclusive, royalty-free licence to host, process, transmit, analyse, reproduce and create derived data from Your Content solely to operate, provide, secure and improve the Service for you, as described in our Privacy Policy. This licence ends when Your Content is deleted from our systems, except for copies we must keep to comply with law or resolve disputes.
4. Where your videos are kept. Video files and your coaching journal are stored on your device. Still frames and related context are sent to our servers and to our AI providers to generate each coaching response. If you delete the App or your data, content stored only on your device may be permanently lost. You are responsible for keeping your own backups.
5. Other people in your videos. You must have every permission needed to record, upload and share Your Content, including consent from anyone else who appears in it, and must comply with the rules of any gym, venue or location where you film. Do not upload content that features a child other than your own child, or that you do not have the right to use.
6. Sharing. The App can create videos for you to share outside the App. You decide whether and where to share them, and you are solely responsible for anything you share and for complying with the terms of the platform you share it on. Once shared, content may be copied or redistributed by others, and we cannot remove it.

6. Acceptable use

You agree not to:

• use the Service in breach of any law or regulation, or to infringe anyone's rights, including privacy and intellectual property rights;
• upload content that is unlawful, sexually explicit, hateful, harassing or violent, or that exploits or endangers anyone;
• access or attempt to access the Service other than through the App; use automated means, scripts or bots; or interfere with, overload, probe or disrupt the Service or its security;
• circumvent, or attempt to circumvent, usage limits, the free session, device checks, subscription verification or any other access control, including by reinstalling the App, using multiple devices or identities, or manipulating requests;
• resell, sublicense or commercially exploit the Service, or use it to provide coaching to others as a business, without our written permission; or
• use the Service or its outputs to build, train or improve a competing product or AI model.

We may suspend or restrict access to the Service if we reasonably believe you have breached this section.

7. Free session, membership and top-ups

1. Free session. We may offer a limited free coaching session. Its limits are shown in the App and may change. It is offered once per person and device, and we may use device checks to enforce this.
2. Membership. Membership is an auto-renewing subscription purchased through Apple's App Store. Payment is charged to your Apple ID account when you confirm purchase. It renews automatically at the end of each billing period unless you turn off auto-renew at least 24 hours before the period ends. Your account is charged for renewal within 24 hours before the end of the current period. You can manage or cancel your subscription in your Apple ID account settings. Cancellation takes effect at the end of the current billing period.
3. Top-ups. Clip top-ups are consumable in-app purchases available to members. Top-up clips are used after the clips included in your membership, and they do not expire while you remain a member. If a top-up purchase is refunded, its unused clips are removed.
4. Fair use. Membership includes the usage limits described in the App at the time of purchase, such as clips and coaching turns per day and per billing period. These limits exist to keep the Service reliable and affordable. We will not describe any plan as unlimited.
5. Prices and changes. Prices are shown in the App before purchase and may vary by country. Apple processes all payments and applies any applicable taxes. We may change prices or plan features in future. Apple will notify you of any subscription price increase and, where required, ask for your consent.
6. Refunds. All purchases are processed by Apple, and refund requests are handled by Apple under its policies. We cannot issue refunds directly. Nothing in these Terms affects any statutory right to a refund or remedy you may have.

8. Consent to use of technical data

You agree that we may collect and use technical data and related information, including information about your device, system and application software, peripherals, usage and diagnostics, and App Attest and DeviceCheck signals. We collect it periodically to facilitate software updates, product support, security and abuse prevention, enforcement of usage limits, and other services related to the App, and to improve our products. We use this information as described in our Privacy Policy.

9. Third-party services and materials

1. The Service relies on third-party services, including Apple (App Store purchases, App Attest and DeviceCheck), Cloudflare (hosting), OpenAI and Anthropic (AI processing) and Google Firebase (crash reporting and analytics). Your use of the App may also be subject to those parties' terms.
2. The App may display, include, link to or make available content, data, information, applications or materials from third parties ("Third-Party Materials"). We are not responsible for examining or evaluating Third-Party Materials or websites, and we do not warrant or endorse them or accept any liability for them. You use Third-Party Materials at your own risk.
3. YouTube. The coach may show demonstration videos published on YouTube by other people. They play in YouTube's embedded player, are credited to their owners as published, and remain their owners' content. The App uses YouTube API Services to show them, and by using the App you agree to be bound by the YouTube Terms of Service. Google's handling of your information when you watch is described in the Google Privacy Policy, and ours in our Privacy Policy.
4. You must comply with any applicable third-party terms when using the App, such as your wireless data service agreement.
5. The Service is not intended for use in situations where timing is critical or where an error, delay or inaccuracy could lead to injury, death or damage. It may be unavailable, interrupted or slower at times, and some features require an internet connection.

10. Changes to the Service and these Terms

We may change, suspend or discontinue any part of the Service at any time, including features, coaching behaviour and supported devices. We will not remove paid-for functionality you are entitled to during a billing period without a legally permitted reason. We may update these Terms from time to time. If we make a material change, we will tell you in the App or by other reasonable means before it takes effect. If you continue using the App after that, the updated Terms apply. If you do not agree, stop using the App and cancel any subscription.

11. Termination

These Terms remain in effect until terminated by you or us. You may end them at any time by deleting the App and cancelling any subscription. Your rights under these Terms end automatically, without notice, if you fail to comply with any of them. We may also suspend or end your access if required by law or to protect the Service or other users. When these Terms end, you must stop using the App and delete all copies of it. Sections 3, 5(d)–(f), 12 to 15 and 17 to 19 survive termination.

12. No warranty

To the maximum extent permitted by applicable law, you expressly acknowledge and agree that you use the App and the Service at your sole risk, and that the entire risk as to satisfactory quality, performance, accuracy and effort is with you. The App, the Service and all coaching and other content are provided "as is" and "as available", with all faults and without warranty of any kind. We and our licensors hereby disclaim all warranties and conditions with respect to the App and the Service, whether express, implied or statutory, including but not limited to implied warranties and/or conditions of merchantability, satisfactory quality, fitness for a particular purpose, accuracy, quiet enjoyment and non-infringement of third-party rights.

We do not warrant against interference with your enjoyment of the App, and we do not warrant that the App or Service will meet your requirements, that it will be uninterrupted, secure or error-free, that coaching will be accurate, complete or suitable for you, that any particular result (including any improvement in technique or performance) will be achieved, or that defects will be corrected. No oral or written information or advice given by us, our authorised representatives or the App's AI coach creates a warranty. Should the App or Service prove defective, you assume the entire cost of all necessary servicing, repair or correction.

If the App fails to conform to any warranty that cannot be disclaimed under applicable law, you may notify Apple, and Apple will refund the purchase price of the App (if any) to you. To the maximum extent permitted by applicable law, Apple has no other warranty obligation of any kind with respect to the App. Any other claims, losses, liabilities, damages, costs or expenses attributable to any failure to conform to any warranty are our sole responsibility, to the extent they cannot be disclaimed under these Terms.

Some jurisdictions do not allow the exclusion of implied warranties or limitations on the applicable statutory rights of a consumer, so some of the above exclusions and limitations may not apply to you.

13. Limitation of liability

To the extent not prohibited by applicable law, in no event will we, our licensors or service providers be liable for personal injury, or any incidental, special, indirect or consequential damages whatsoever. This includes, without limitation, damages for loss of profits, loss of data or content, business interruption, or any other commercial damages or losses, arising out of or related to your use of or inability to use the App or the Service, any coaching or content, or any exercise you perform. This applies however caused, regardless of the theory of liability (contract, tort or otherwise), and even if we have been advised of the possibility of such damages.

In no event will our total liability to you for all damages (other than as may be required by applicable law in cases involving personal injury) exceed the amount of fifty US dollars (US$50.00) or its equivalent in your local currency. These limitations apply even if the above remedy fails of its essential purpose.

What we do not exclude. Nothing in these Terms excludes or limits any liability that cannot be excluded or limited under applicable law. This includes, where applicable, liability for death or personal injury caused by negligence, liability for fraud or fraudulent misrepresentation, and your statutory rights as a consumer, including under the UK Consumer Rights Act 2015 or equivalent laws where you live. Some jurisdictions do not allow the limitation of liability for personal injury, or of incidental or consequential damages, so some of these limitations may not apply to you.

14. Indemnity

To the extent permitted by applicable law, you agree to indemnify us against claims, losses and reasonable costs brought by third parties arising from: Your Content; content you share outside the App; your breach of these Terms; or your violation of any law or the rights of any third party, including anyone who appears in your videos.

15. Product claims and intellectual property claims

1. We, not Apple, are responsible for addressing any claims by you or any third party relating to the App or your possession and/or use of it. This includes, but is not limited to: (i) product liability claims; (ii) any claim that the App fails to conform to any applicable legal or regulatory requirement; and (iii) claims arising under consumer protection, privacy or similar legislation.
2. If any third party claims that the App, or your possession and use of it, infringes that third party's intellectual property rights, we, not Apple, will be solely responsible for the investigation, defence, settlement and discharge of that claim, to the extent required by these Terms.

16. Legal compliance and export

You may not use or otherwise export or re-export the App except as authorised by United States law and the laws of the jurisdiction in which the App was obtained. In particular, but without limitation, the App may not be exported or re-exported: (a) into any U.S.-embargoed countries; or (b) to anyone on the U.S. Treasury Department's Specially Designated Nationals List or the U.S. Department of Commerce's Denied Persons List or Entity List. The same applies to any equivalent UK or EU sanctions list. By using the App, you represent and warrant that you are not located in a country that is subject to a U.S. Government embargo, or that has been designated by the U.S. Government as a "terrorist supporting" country, and that you are not listed on any U.S. Government list of prohibited or restricted parties. You also agree that you will not use the App for any purpose prohibited by applicable law, including the development, design, manufacture or production of nuclear, missile, chemical or biological weapons.

17. U.S. Government end users

The App and related documentation are "Commercial Items", as that term is defined at 48 C.F.R. §2.101, consisting of "Commercial Computer Software" and "Commercial Computer Software Documentation", as those terms are used in 48 C.F.R. §12.212 or 48 C.F.R. §227.7202, as applicable. Consistent with those sections, they are being licensed to U.S. Government end users (a) only as Commercial Items and (b) with only those rights as are granted to all other end users under these Terms. Unpublished rights are reserved under the copyright laws of the United States.

18. Governing law and disputes

These Terms, and any dispute or claim arising out of or in connection with them or the App, are governed by the laws of England and Wales. The courts of England and Wales have non-exclusive jurisdiction. If you are a consumer, you also benefit from any mandatory protections of the law of the country where you live, and you may bring proceedings in the courts of that country. The United Nations Convention on Contracts for the International Sale of Goods does not apply to these Terms.

19. General

1. Third-party beneficiary. You and we acknowledge and agree that Apple and Apple's subsidiaries are third-party beneficiaries of these Terms. Upon your acceptance of these Terms, Apple will have the right (and will be deemed to have accepted the right) to enforce them against you as a third-party beneficiary. Otherwise, no one other than you and us has any right to enforce these Terms.
2. Severability. If any provision is found invalid or unenforceable, it will be enforced to the maximum extent permissible, and the remaining provisions will remain in full force and effect.
3. No waiver. Our failure or delay in enforcing any provision is not a waiver of our right to do so later.
4. Assignment. You may not transfer your rights or obligations under these Terms. We may transfer ours to another organisation in a way that does not reduce your rights.
5. Entire agreement. These Terms, together with our Privacy Policy and any terms presented at the point of purchase, are the entire agreement between you and us about the App. Where applicable, they operate alongside the Apple Media Services Terms and Conditions.
6. Language. These Terms are written in English. Any translation is for convenience only.

20. Contact

Questions, complaints or claims about the App should be directed to:

Leon Johnstone
Flat 7, Danescroft, Brent Street
London NW4 2QH
United Kingdom
Email: support@callustraining.com