A free iOS app that uses AI and spaced repetition to help musicians practice smarter, retain repertoire longer, and build consistent habits.

Yes, free to download on the App Store. Pro subscription available for unlimited AI and cloud features.

What instruments does it support?

All instruments. Piano, guitar, violin, cello, bass, winds, voice — the AI adapts to any repertoire.

How does the AI work?

It reads the user’s session history and predicts which pieces are about to be forgotten, then schedules them for review at the optimal moment. Based on cognitive science research on memory consolidation.

How is it different from other practice apps?

Most practice apps are passive timers. Sostenuto actively adapts: it tells you what to practice, when, and for how long — based on real retention data. The full feedback loop (heatmap + grading + AI + recording) sets it apart.

Does it work for beginners?

Yes. The AI calibrates to any level, from first-month students to conservatory audition prep.

Is Android supported?

Not yet. iOS only (iPhone and iPad). Android is planned for a future release.

What is the Gems system?

An achievement system that uses behavioral science (streaks, milestones, smart reminders) to make daily practice a sustainable habit.

Terms of Service

Sostenuto Last updated: 15 March 2026

1. Agreement to Terms

By downloading, installing, or using Sostenuto ("the App"), you agree to be bound by these Terms of Service ("Terms"). If you do not agree, do not use the App.

Sostenuto is operated by Valerio De Feo ("we", "us", or "our"), an independent developer. These Terms govern your use of the App on Apple iOS devices.

2. Use of the App

You may use Sostenuto to:

Log and track your music practice sessions
Record audio and video of your own practice
View AI-generated practice guidance ("Maestro AI")
Share practice analytics with your teacher via a generated link

You may not use Sostenuto to:

Reverse-engineer, decompile, or disassemble any part of the App
Attempt to gain unauthorised access to any backend systems
Upload, transmit, or share content that infringes third-party intellectual property rights
Violate any applicable law or regulation
Scrape, systematically extract, or reverse-prompt the Maestro AI to reproduce, copy, or distribute the underlying training data, music theory library, or reference material it relies upon.

3. Accounts & Authentication

Sostenuto uses Supabase for authentication. You may use the App anonymously (limited features) or create an account with your email address. You are responsible for maintaining the confidentiality of your account credentials. We are not liable for any loss arising from unauthorised access due to your failure to keep credentials secure.

4. Pro Subscription

Sostenuto offers a "Pro" subscription via Apple's In-App Purchase system (processed by RevenueCat).

Billing: Charges are applied to your Apple ID account at confirmation of purchase. Subscriptions auto-renew unless cancelled at least 24 hours before the end of the current period.
Cancellation: You can cancel any time in your iOS device's Subscriptions settings (Settings > [Your Name] > Subscriptions).
Refunds: All refund requests are subject to Apple's refund policy. We do not process refunds directly.
Free features: Core logging, metronome, and basic AI queries remain free as long as we offer them. We reserve the right to adjust the free tier with reasonable notice.

5. AI Features (Maestro AI)

Maestro AI is powered by third-party AI models (currently OpenAI). AI-generated content is provided for informational and educational purposes only. It may contain errors or inaccuracies. You should exercise your own judgment and not rely solely on AI guidance for health, safety, or professional music education decisions.

We do not guarantee the pedagogical accuracy or effectiveness of the AI's suggested routines. Maestro AI responses are synthesized probabilistically, including from third-party reference materials in our database, and may hallucinate or provide technically flawed advice. You agree that we bear no liability for any lack of musical progress, poor audition results, or technical habits resulting from your reliance on the App's instruction.

AI queries may be processed by third-party servers. See our Privacy Policy for details.

6. Audio & Video Recordings

All recordings you make within the App are stored locally on your device and (if you are a Pro subscriber with cloud sync enabled) in your private, encrypted Supabase storage bucket. We do not access or use your recordings for any purpose other than syncing them to your own account.

7. Teacher Sharing

The "Teacher Share" feature generates a read-only analytics link. By generating a link, you grant anyone with that link access to the aggregate statistics described in the shared page. You can revoke access at any time by generating a new token, which deactivates the previous one.

8. Intellectual Property

The App, its design, UI, branding, and all associated content are the intellectual property of Valerio De Feo. Nothing in these Terms grants you any ownership interest in the App.

Your right to use Maestro AI is strictly a limited license to receive contextual practice guidance. You are granted no license, ownership, or copyright to the proprietary database of pedagogical knowledge from which the AI draws its responses.

9. Disclaimer of Warranties

THE APP IS PROVIDED "AS IS" WITHOUT WARRANTIES OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING, WITHOUT LIMITATION, WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. WE DO NOT WARRANT THAT THE APP WILL BE UNINTERRUPTED, ERROR-FREE, OR SECURE.

10. Limitation of Liability

TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, IN NO EVENT SHALL WE BE LIABLE FOR ANY INDIRECT, INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES ARISING FROM YOUR USE OF THE APP, EVEN IF WE HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. OUR TOTAL LIABILITY SHALL NOT EXCEED THE AMOUNT YOU PAID FOR A PRO SUBSCRIPTION IN THE 12 MONTHS PRIOR TO THE CLAIM.

11. Changes to These Terms

We may update these Terms from time to time. We will notify you of material changes by posting the updated Terms in the App or via email. Continued use after changes constitutes acceptance.

12. Governing Law

These Terms are governed by and construed in accordance with the laws of Italy, without regard to its conflict of law provisions. Any disputes shall be subject to the exclusive jurisdiction of the courts of Italy.

13. Contact

For questions about these Terms, contact: [email protected]