Privacy Policy

This Privacy Policy explains how Best Day Labs ("we", "us", or "our") handles your information when you use the Keys mobile application (the "App").

1. Video imports & audio transcription

When you share or paste a video link, our servers download the audio from the source (TikTok, Instagram, YouTube, etc.) and pass it to third-party machine-learning services — primarily Modal, with Replicate used as a fallback — to extract the piano part as MIDI. The same processing applies when you use related features such as vocal removal or piano-cover generation. Audio is processed transiently for the duration of the request and is not permanently stored on our servers. The resulting MIDI and note data are returned to your device and saved to your library.

2. Microphone (Learn Mode)

Learn Mode listens through your device microphone to detect which notes you play. Audio captured by the microphone is processed entirely on your device — it is never uploaded, recorded, or stored anywhere. The microphone is only active while Learn Mode is enabled.

3. Camera & photos (sheet music scanning)

If you use the sheet music scanning feature, the captured image is sent to a third-party AI service (Anthropic) for transcription. The image is processed in the request and discarded; we do not retain uploaded sheet music images. If you select a profile photo from your Photo Library, that image is stored locally on your device and is not uploaded to our servers unless you publish a song to the community catalog (see below).

4. Account & sign-in

Keys signs you in anonymously through Supabase Auth so your library and votes can sync across devices. We do not collect a password, email address, or name at sign-in, and we do not use Sign in with Apple. If you publish a song to the community catalog, your display name and (if you set one) profile photo are associated with that contribution and visible to other Keys users.

5. Community catalog

If you choose to publish a transcription to the public catalog, the song's metadata (title, artist, source URL, MIDI, note data) is stored in Supabase, a third-party database and storage service. Published catalog entries are visible to all Keys users. You may request removal of your contributions at any time by contacting us.

6. Subscriptions

Keys is a paid subscription app. All payments are processed by Apple through the App Store; we do not receive or store your payment information. Subscription status is checked via Apple's StoreKit framework.

7. Local data

Your song library, playback preferences, achievements, and playback history are stored locally on your device using Apple's SwiftData framework. This data is not transmitted to us.

8. Third-party services

We use the following third parties to operate the App. Each handles your data according to their own privacy policies:

• Apple — App Store, StoreKit, and subscription billing.
• Supabase — anonymous authentication, database, file storage.
• Modal — piano transcription machine-learning models (primary).
• Replicate — piano transcription machine-learning models (fallback).
• Anthropic — sheet music optical recognition.
• Railway — hosting for our backend servers that process video imports.
• PostHog — pseudonymous product analytics (see section 9).
• TikTok — advertising attribution and ad-performance measurement (see section 9).

9. Product analytics

We use PostHog, a privacy-respecting product analytics service, to understand how the App is used in aggregate — for example, which features are popular, where users encounter errors, and how the import flow performs. The events we record describe interactions (e.g. "import succeeded", "learn mode started") and are keyed to your app-generated, pseudonymous Supabase user ID; PostHog may also process technical metadata such as device type and IP address as part of delivering the service. This information is pseudonymous rather than fully anonymous, because the app-generated ID is persistent. Through PostHog we do not collect screen recordings, full keystroke logs, precise location data, contacts, or browsing history outside the App.

Advertising and attribution. We use the TikTok Business SDK to measure how our own advertising performs — for example, whether an install or subscription followed from a TikTok ad. With your permission (requested through Apple's App Tracking Transparency prompt), this includes your device's advertising identifier (IDFA); if you decline, attribution falls back to non-identifying signals. We use this only to measure and improve our own marketing, not to build advertising profiles, and you can change your choice at any time in iOS Settings → Privacy & Security → Tracking.

10. Data retention

We keep information only as long as needed for the purposes described in this policy:

• Imported audio — held transiently in memory only for the duration of the transcription request, then discarded.
• Sheet music images — processed within the request and not retained.
• Account & catalog data — retained until you delete your account or request removal of your contributions, after which it is deleted from active systems within a reasonable period (subject to routine backup cycles).
• Analytics events — retained by PostHog in aggregate for product-improvement purposes.

11. International users & data transfers

We operate from the United States, and our service providers may process your information in the United States and other countries. If you access the App from outside the United States, you understand that your information may be transferred to, stored, and processed in the United States, where data-protection laws may differ from those in your jurisdiction.

12. Your privacy rights (GDPR & CCPA)

Depending on where you live, you may have rights regarding your personal information, including the right to access, correct, delete, or port your data, and to object to or restrict certain processing. Because Keys is designed around anonymous, on-device, and pseudonymous data, the personal information we hold about any individual is limited.

You can delete your Keys account and associated catalog data at any time by emailing us at the address below, and we will delete it from our active systems. We will not discriminate against you for exercising these rights.

We do not sell your personal information. Other than the advertising-attribution data described in section 9 — which is shared with TikTok only with your App Tracking Transparency consent and solely to measure our own ads — we do not share your personal information for cross-context behavioral advertising, as those terms are defined under the California Consumer Privacy Act (CCPA/CPRA).

13. Children's privacy

Keys is not directed to children under 13, and we do not knowingly collect personal information from children under 13. While the App carries a 4+ content rating (meaning its content is suitable for general audiences), it is intended for use by individuals aged 13 and older. If you believe a child under 13 has provided us with personal information, please contact us and we will delete it.

14. Changes to this policy

We may update this Privacy Policy from time to time. The "Effective" date above will reflect the most recent update. Continued use of the App after changes means you accept the revised policy.

15. Contact

If you have any questions about this Privacy Policy or wish to exercise a privacy right, please contact us at support@bestdaylabs.com.