Notalune. Privacy Policy

Effective date: the release of Notalune 1.3 (October 2026). Previous version: July 12, 2026.

Privacy at a glance

• Notalune collects no data about you. None.
• Everything the app does, photographing sheet music, recognizing notes, showing note names, happens entirely on your device. The app contains no networking code and never connects to the internet.
• Listening practice (from version 1.3) uses the microphone only while one of its screens is open and listening. The sound is analysed live on your device and is never recorded, stored or sent.
• There are no accounts, no analytics, no advertising, no tracking, and no third-party SDKs that phone home.
• Your photos and saved pieces stay in the app's own storage on your device. You can delete them at any time.
• One optional, off-by-default feature ("Help improve recognition") saves small correction snippets locally on your device. Nothing is ever uploaded automatically. If you want to help, you send them to us manually. Something you send us yourself (these snippets, a message or a listening log, see section 5) is the only way any data ever reaches us.
• Purchases are handled by Apple. We never see your payment details.

The rest of this document spells that out in full.

1. Who we are

Notalune is developed by daylight.studio (sole developer). You can reach us at info@notalune.com with any privacy question.

2. What the app does with your photos

Notalune helps beginners read printed piano sheet music by overlaying note names (C D E F G A H / English / solfège) on photos of the score.

• Photos are captured with your camera, or imported from your photo library using Apple's system photo picker.
• All image processing and music recognition run on your device, using a machine-learning model bundled inside the app. No image, or any data derived from an image, ever leaves your device through the app.
• The app has no networking capability at all: no servers, no cloud processing, no telemetry, no crash reporting services.

3. Data stored on your device

The app stores the following only in its local app storage on your device:

• Pieces (skladby): the photos you scan and the recognition results, saved as files in the app's private documents folder so you can reopen them later.
• Recent readings: a short rolling history of your most recent scans (the app keeps the latest 20 and discards older ones automatically).
• Settings: your preferences (note-name style, language, metronome settings, etc.), stored in the app's local preferences.

This data never leaves your device unless you export it yourself (for example, printing or sharing a PDF of a piece, an action you take deliberately through the system share sheet). Deleting a piece in the app, or deleting the app, removes this data. Note: if you use iCloud device backups, your device may include the app's data in your backup, that is a function of iOS under your control, not something the app does.

4. Optional: "Help improve recognition"

The app has an opt-in setting (off by default) called Help improve recognition (Czech: Pomáhat zlepšovat rozpoznávání). If you turn it on:

• When you correct a wrongly recognized note, the app saves a small image crop of that note together with your correction, locally on your device only.
• Nothing is uploaded. There is no automatic transmission of any kind, ever.
• You can review the size of this collection and delete it at any time in Settings.
• If you want to help improve the app, you can manually export these snippets via the standard iOS share sheet (for example AirDrop or Mail) and send them to us at info@notalune.com. This only ever happens by your explicit action.

5. If you send us something

If, and only if, you voluntarily send us something, we receive it by email or AirDrop: improvement snippets (section 4), a message written with "Write a message" in Settings, or a listening log (section 7). Those transfers, always started by you, are the only cases in which we process any data from you, and here is how we handle them under the EU General Data Protection Regulation (GDPR):

• Controller: David Christian Lichtag (trading as daylight.studio), Březová 735/103, 637 00 Brno, Czech Republic, contact: info@notalune.com.
• What we receive: small image crops of printed sheet music with your correction labels, plus whatever your email/AirDrop transfer naturally includes (e.g. your email address). Crops of printed music are normally not personal data, but a crop could incidentally contain personal elements (handwritten annotations, a name written on the score).
• Messages and listening logs: a message reaches us with one line the app adds to help us answer (app version, device model, iOS version and app language). A listening log holds loudness and pitch numbers only, never sound. We use both only to answer you and to fix what you report, and delete them once that is done, unless you ask us to keep them.
• Purpose: improvement snippets are used to improve the on-device music-recognition model; messages and listening logs to answer you and fix what you report. Nothing else. We do not publish or redistribute anything you send. Please only send crops of material you may lawfully share with us for this purpose (see the Terms of Use); the crops are small excerpts by design (roughly one measure of context).
• Legal basis: your consent (Art. 6(1)(a) GDPR), given by the act of deliberately sending us the data. You may withdraw consent at any time with effect for the future.
• Retention: we keep shared snippets until they have been incorporated into model training, after which the raw snippets are deleted from our working set; messages and logs as described above. On request we will delete your shared data earlier, at any time.
• Recipients: no one. We do not share, sell, or transfer this data to anyone else, and we do not use it for anything except the purposes described in this section.
• Your rights: you have the right of access, rectification, erasure, restriction of processing, data portability, and objection (Arts. 15–21 GDPR). Email info@notalune.com to exercise them. You also have the right to lodge a complaint with a supervisory authority, in the Czech Republic, the Office for Personal Data Protection (Úřad pro ochranu osobních údajů, www.uoou.cz).
• No automated decision-making or profiling takes place.

For everything the app does on your device (sections 2–4), you remain in sole control of the data: it is processed locally, under your control, and we, the developer, never have access to it.

6. Purchases

Optional paid features ("Notalune Pro") are sold exclusively through Apple's App Store using Apple's StoreKit. Payment, billing details, and receipts are handled entirely by Apple under Apple's privacy policy. We never receive your name, payment details, or Apple ID. The app checks your entitlement locally through StoreKit.

7. Permissions

• Camera: used solely to photograph sheet music for recognition.
• Microphone (from version 1.3): used only while listening practice, the note quiz or Microphone setup is open, screens you open yourself; the microphone turns off when you leave them. The sound is analysed live on your device to tell which note you played. It is never recorded, stored or sent. To help explain a misheard note, the app keeps a short technical log of that analysis in its memory: loudness and pitch numbers only, no sound. It leaves your device only if you tap "Share the log" in Microphone setup and send it yourself (section 5); for that moment only it is written to a temporary file, deleted when the share sheet closes. You can turn microphone access off at any time in the iOS Settings app (Notalune, or Apps → Notalune on iOS 18 and later).
• Photo library: the app uses Apple's system photo picker (PhotosPicker), which lets you hand the app individual photos without granting it any access to your library. No photo-library permission is requested.
• The app requests no other permissions: no location, no contacts, no Bluetooth, no local network.

8. No third-party services

The app embeds two open-source software components (OpenCV and a YOLOX-based recognition model) that run entirely offline and do not communicate with anyone. There are no third-party analytics, advertising, crash-reporting, or social SDKs. A complete list of third-party components is in the app's third-party notices.

One transparency note: Apple may show us aggregated, anonymous App Store statistics (such as download counts, sessions, or crashes) for users who chose to share analytics with developers in their iOS settings. That is Apple's processing, governed by Apple's privacy policy and your iOS settings, the app itself still transmits nothing, and we receive nothing that identifies you.

9. Children

Notalune is suitable for use by children learning piano. Because the app collects no data whatsoever, from children or anyone else, no parental consent mechanisms are required for data processing, and the app is compliant by design with children's privacy rules such as COPPA (US) and GDPR rules on children's consent (GDPR-K): there is simply no collection to consent to. The optional sharing described in sections 4–5 requires deliberate manual action through the system share sheet; we ask that children not send us improvement data without a parent or guardian's involvement, and if we learn that data was sent to us by a child without such involvement, we will delete it.

10. Data security

Your data's security on the device is provided by iOS's built-in protections (sandboxing and device encryption). Since no data is transmitted by the app, there is no transmission to secure. The few files you may choose to email us are protected in transit by your email provider's transport security.

11. The website, notalune.com

Everything above is about the app. The website is a separate thing and this section is the only part of this policy that describes it. The app has no network code, so nothing on the website can change what the app does.

Cookies and similar storage. The website asks you, on your first visit, whether it may count visits and whether it may show you our advertising elsewhere. Both are off until you say yes, and nothing third-party is loaded before you answer. You can change the answer at any time through the "Cookie settings" link in the footer of every page.

• Necessary. Your answer is remembered in a first-party cookie named notalune_consent, set by this site and readable only by it. It holds nothing but the two yes-or-no values and a version number, identifies nobody, and is never sent to a third party. It lasts a year if you agreed to something and six months if you refused, after which we ask once more. This cookie is the only storage the site uses when you decline everything, and it is not set at all until you answer. The one exception is the metronome, which remembers its tempo and settings in your browser so they are there next time; nothing of it is sent anywhere.
• Visit statistics, only if you agree. Aggregate counts of visits and pages read. We do not learn who you are.
• Advertising, only if you agree. This is the one that shares data with Meta Platforms Ireland Limited, so that we can show our own advertising to people who have visited the site. Meta acts as an independent controller for what it does with that data; its own policy governs it.

As of the effective date above, neither of the optional two is switched on. There is therefore nothing to consent to, so the question is not asked: no banner appears, no cookie is set, and the site loads no third-party resources at all. The banner turns itself on when a service is configured, and this section will name that service before it runs.

The release-notification form (retired). Before release, the site offered a form to be told when Notalune reached the App Store. The app is out, so the form is gone. If you left your address, it was stored in nothing but our mailbox, you receive one message announcing the release, and the address is then deleted, as the form promised. There was no mailing list, no newsletter and no third-party mailing service.

Server logs. Our hosting provider (Active24, Czech Republic) keeps ordinary web-server logs, which include IP addresses, for the short period it needs them to operate and secure the service. That is the host's processing as our processor. We may look at the aggregate visitor statistics the host generates from those logs (visit counts, which pages were read, roughly where from). Those statistics are counted on the server, set nothing on your device and identify nobody, which is why the site can offer them without asking you anything.

Notalune in ChatGPT. The Notalune plugin runs on our server at notalune.com/mcp/. When ChatGPT uses it, ChatGPT’s servers, not your device, send that server what to show, written by ChatGPT from your conversation: a chapter, a clef and range, notes, a tempo, the panel’s language, and sometimes a short title such as the name of a piece. ChatGPT may attach technical details of its own; the server ignores them. It uses the request only to draw the panel and keeps nothing. Active24’s server logs described above record the request, with OpenAI’s address rather than yours. What you play stays in the panel, which remembers only your choice of note names, hints, rows or one note at a time, and metronome settings, within ChatGPT. Only if you press “Ask ChatGPT” does the panel put your score and missed notes into the conversation, as if you had typed them. The Notalune link opens this website as an ordinary visit; its App Store links are marked so that Apple counts those downloads, in total only. ChatGPT itself is OpenAI’s service, governed by OpenAI’s privacy policy. Legal basis: our legitimate interest in providing the service you asked ChatGPT to use (Art. 6(1)(f) GDPR).

Your rights. For anything the website holds about you, the GDPR rights in the Czech and EU sense apply: access, correction, erasure, restriction, objection, and portability. Write to info@notalune.com. You may also complain to the Czech data protection authority (Úřad pro ochranu osobních údajů, uoou.cz).

12. Changes to this policy

If we ever change how the app handles data (for example, if a future version adds any online feature), we will update this policy, change the effective date above, and describe the change in the App Store release notes before it takes effect. The same applies to section 11: no analytics or advertising service is switched on before it is named there.

13. Contact

daylight.studio, info@notalune.com