These Terms of Service ("Terms") govern your use of the String AI app. You agree to these Terms when you sign up for String AI (for a student under 14, the parent or guardian who gives consent accepts them on the student's behalf — section 2). If you do not agree, please do not sign up or use the app. Questions: stringaiapp@gmail.com.
1. The service
String AI is an AI-powered practice app for violin, viola, and cello. It listens to your playing and watches your posture to give automated feedback on intonation, rhythm, tone, dynamics, and posture, and it plans practice missions and drills. Coaching messages, practice plans, and weakness diagnoses in this service are produced by generative artificial intelligence (OpenAI API). The app is an educational and practice aid — not a substitute for a qualified teacher, and not a medical, physical-therapy, or health service.
From October 18, 2026, section 1 reads: String AI is an AI-powered practice app for violin, viola, and cello. It listens to your playing and watches your posture to give automated feedback on intonation, rhythm, tone, dynamics, and posture, and it plans practice missions. Piece introductions and practice plans are written by generative artificial intelligence (OpenAI API) and are labeled as AI coaching in the app; scoring, weakness diagnosis, and the feedback after each take are produced by the app’s own rules and prepared sentences. The app is an educational and practice aid — not a substitute for a qualified teacher, and not a medical, physical-therapy, or health service.
2. Eligibility and minors
You must be able to form a binding contract to use String AI. Students under 14 may use the app only with the explicit consent of a parent or legal guardian, who accepts these Terms on the student's behalf. A parent or guardian who provides consent is responsible for supervising the minor's use and may review, export, or delete the minor's data at any time. We apply a 14-year threshold globally, consistent with COPPA (US) and PIPA (Korea).
From October 18, 2026, section 2 reads: Students under 14 may use String AI only with the explicit consent of a parent or legal guardian, who accepts these Terms on the student's behalf. If you are a minor under the law where you live (under 19 in Korea; under 18 in most US states), you may use String AI with the agreement of a parent or guardian who has read these Terms. A purchase made by a minor may be cancelled as the applicable law allows. A parent or guardian who provides consent is responsible for supervising the minor's use and may review, export, or delete the minor's data at any time. We apply a 14-year threshold globally, consistent with COPPA (US) and PIPA (Korea).
3. Your account
You are responsible for keeping your account credentials secure and for activity under your account. Provide accurate information (a valid email and display name). The age range you select must be accurate. If you are creating an account for a child under 14, you must select the child's age range and provide a parent or guardian email so that consent can be obtained. Registering a child as an adult violates these Terms; String AI relies on the age you provide. You may delete your account at any time from Profile > Privacy & Data; deletion permanently removes your personal data within 30 days, as described in our Privacy Policy.
4. Subscriptions, billing, and auto-renewal
String AI offers optional auto-renewing monthly subscriptions. All purchases are processed by the Apple App Store or Google Play — we never handle or store your payment details.
| Plan | Lesson time |
|---|---|
| Basic | 15 min/day · 450 min/month |
| Casual | 30 min/day · 900 min/month |
| Standard | 45 min/day · 1350 min/month |
The price of each plan is the amount shown in the Apple App Store or Google Play purchase sheet at the moment you confirm the purchase, in your local currency; that displayed price is the binding price and it may vary by region and applicable tax. A plan that is no longer offered to new subscribers (for example the former Pro plan) continues for existing subscribers until they cancel or change plans in the store. Each subscription renews automatically for successive one-month periods and your payment method is charged at the start of each period, until you cancel. You can cancel anytime in your Apple App Store or Google Play account settings; cancellation takes effect at the end of the current billing period, and you keep access until then. Managing and canceling subscriptions is done through the store, not through us.
5. Free trial
String AI may offer a 7-day free trial. The trial does not automatically convert into a paid subscription — when it ends, you simply choose a plan if you wish to continue, and no charge is made unless you actively subscribe.
6. Refunds
Because payments are processed by Apple and Google, refunds are governed by their policies and handled through them (Apple: reportaproblem.apple.com; Google Play: Play Store order history). We are glad to help you with subscription questions at stringaiapp@gmail.com, but we cannot directly issue store refunds.
Right of withdrawal (Republic of Korea). If you are in the Republic of Korea, you may request withdrawal of a subscription purchase within 7 days of payment. Because Apple and Google process the payment, send the request through the store — Apple: reportaproblem.apple.com; Google Play: your Play Store order history. Approved requests are refunded to your payment method on the store's timeline. Withdrawal may be limited for the portion of the service you have already used (Act on Consumer Protection in Electronic Commerce, Article 17(2)). So that you can evaluate the service before that limit applies, we provide a 7-day free trial: nothing is charged during the trial. Questions: stringaiapp@gmail.com.
7. AI feedback disclaimer
Feedback, scores, diagnoses, and practice plans are generated automatically and may be incomplete or incorrect. They are guidance, not professional instruction. Use your own judgment and, for serious technique or health concerns, consult a qualified teacher or medical professional. If you feel pain or discomfort while playing, stop and seek appropriate advice — the app cannot assess injury risk.
8. Acceptable use
Do not reverse-engineer, resell, or misuse the app; do not upload unlawful content; do not attempt to disrupt or gain unauthorized access to our systems. We may suspend accounts that violate these Terms or applicable law.
Teacher accounts. (Takes effect on October 18, 2026.) If you use String AI as a teacher, the student information you can see in the app — such as the student’s name, scores, practice records, practice journal, schedules, and homework — is shared with you only so that you can teach that student. You agree to: (a) use it only to teach that student; (b) keep it confidential, and not copy, screenshot, export, or post it, take it out of the app, or show it to anyone other than that student and their parent or guardian; (c) not use the app to collect contact details from students or parents, and not use student information to contact them about anything unrelated to their lessons; (d) when a connection ends, stop using that student’s information and delete any copy you made of it; and (e) keep any device you use to see student information secure, for example with a screen lock, and not alter or spread that information (commitment (e) takes effect on November 11, 2026 — 30 days after posting, because it adds a duty; a teacher who confirms it in the app is bound from that confirmation). If you break these commitments, we may suspend teacher features or your account. The app asks you to confirm these commitments and records the version and time you confirmed them.
9. Intellectual property
The app, its software, design, and original content are owned by String AI and its licensors. We grant you a personal, non-transferable, non-exclusive license to use the app for its intended purpose. Sheet music and other third-party materials remain the property of their respective owners. Your practice data belongs to you.
My Scores (sheet music you import). My Scores is available in student accounts and is for your personal, non-commercial practice. Import music into My Scores only if you have the right to use it — for example, sheet music you bought, music you wrote, or sheet music whose copyright has expired. Do not import music you are not allowed to copy, and do not remove copy protection to import it; locked PDFs cannot be opened. Imported files and anything the app makes from them stay only on your device; they are not backed up and cannot be recovered once deleted (our Privacy Policy explains when that happens). String AI does not receive, review, store, or share them, and the app has no feature for sending them to anyone. A title you type for a score is handled as described in our Privacy Policy. You are responsible for making sure your use follows copyright law. This does not limit any responsibility String AI has under applicable law. Importing music gives you no rights in it beyond those you already have. The app’s reading of your music may contain mistakes; check it before you practice.
From October 19, 2026, the backup sentence of the “My Scores” paragraph reads: Imported files and anything the app makes from them stay only on your device, in an app folder that the app sets to be left out of iCloud and Google device backups, so you may not be able to recover them once deleted (our Privacy Policy explains when that happens).
Copyright complaints. (Takes effect on October 18, 2026.) If you believe that material in String AI — such as sheet music, recordings, or images in the library — infringes your copyright, email stringaiapp@gmail.com with: your name and contact details; the work you believe is infringed; where the material appears in the app; a statement that you believe in good faith that the use is not authorized; a statement that the information in your notice is accurate and that you are the owner or are authorized to act for the owner; and your physical or electronic signature. We will review the notice and, where appropriate, remove the material or make it unavailable. Music imported into My Scores stays on the user’s device and is never received by us.
10. Disclaimers and limitation of liability
The app is provided "as is" and "as available," without warranties of any kind to the fullest extent permitted by law. To the maximum extent permitted by applicable law, String AI is not liable for indirect, incidental, or consequential damages, or for any loss arising from reliance on AI feedback. Nothing in these Terms limits liability that cannot be limited by law (including certain rights of consumers and minors).
11. Changes to these Terms
We may update these Terms as the service evolves. We post changes on this page with their effective date before they take effect — at least 7 days before, or at least 30 days before if a change is unfavorable to users — and we also let you know in the app about important changes. If you do not agree with a change, you may stop using String AI and delete your account at any time (section 13).
12. App Store (Apple) additional terms
If you download String AI from the Apple App Store, the following apply: (a) these Terms are between you and String AI only, not Apple, and Apple is not responsible for the app or its content; (b) Apple has no obligation to provide any maintenance or support for the app; (c) in the event the app fails to conform to any applicable warranty, you may notify Apple and Apple will refund the purchase price (if any), and to the maximum extent permitted by law Apple has no other warranty obligation; (d) Apple is not responsible for addressing any claims relating to the app, including product-liability, legal/regulatory, or intellectual-property claims; (e) you represent that you are not located in a country subject to a US Government embargo and are not on any US Government restricted-parties list; and (f) Apple and its subsidiaries are third-party beneficiaries of these Terms and may enforce them against you.
13. Termination
You may stop using String AI and delete your account at any time from Profile > Privacy & Data. We may suspend or terminate your access if you materially breach these Terms or applicable law, or where required to protect users or comply with legal obligations. On termination, your right to use the app ends; provisions that by their nature should survive (such as disclaimers, limitation of liability, intellectual property, and governing law) continue to apply. Your subscription, if any, is managed and cancelled through the Apple App Store or Google Play, not by account deletion alone.
14. Severability and entire agreement
If any provision of these Terms is found unenforceable, the remaining provisions stay in full effect. These Terms, together with our Privacy Policy, are the entire agreement between you and String AI regarding the app. Our failure to enforce any right is not a waiver of that right.
15. Governing law and contact
These Terms are governed by the laws of the Republic of Korea, without regard to conflict-of-law rules, and subject to any mandatory consumer-protection rights of your country of residence. Questions or notices: stringaiapp@gmail.com.