Privacy Policy

Version 1.1 · Effective 14 October 2026 · Last updated 14 October 2026

This Privacy Policy explains how DQCLabs (“we”, “us”) collects, uses and shares information when you use the Cajón Studio app for iOS and Android and the website virtual-cajon.web.app. For users in the European Economic Area (EEA), the United Kingdom and Switzerland, we are the data controller for the processing described here, except where a third party acts as an independent controller.

1. Information we collect

No account

You do not need to create an account or sign in to use Cajón Studio, and we do not operate a server of our own that stores information about you.

Information that stays on your device

The following is stored only on your device, inside the app’s private storage (its “sandbox”). It is not sent to us, and it is removed when you delete the app or clear its data:

• your settings — playing, audio, latency and timing calibration, language, accessibility, and your diagnostics choice;
• your lesson progress — completed lessons, best scores and, if you turn it on, your daily streak;
• grooves you create or save, and your favourites;
• recordings you make in the Studio, with the timing of your strokes (used only to draw the take video). They leave your device only when you share them yourself through your phone’s system share sheet, and then go only to the app or person you choose;
• songs you choose for “Play along with a song”. The app reads the file you pick, keeps a decoded copy in its private storage so it can loop it, and never uploads it. You can remove a song at any time; only use music you have the right to play;
• a class assignment you join with a teacher’s code (its name and lesson list). Teacher mode creates these codes on the device; the code and any progress report travel only when you share them yourself.

What you play — the strokes you tap on the screen and how you play them — is processed on your device to produce sound and to score lessons. It is not stored beyond your lesson results and is never sent anywhere.

Information that leaves your device

• Usage and crash information — only if you turn on diagnostics. See section 4.
• Advertising information — free users only. Such as your IP address and the approximate location derived from it, device information, the device advertising identifier where you allow it (see section 5), and interactions with ads (views and taps). This is collected by the Google Mobile Ads SDK and Google’s User Messaging Platform when consent is checked and when ads are requested and shown.
• Purchase information if you buy Pro or Remove ads, or restore a purchase: the product, purchase date, price, currency, store country and your entitlement status (whether Pro or Remove ads is active), together with an anonymous app user identifier created by RevenueCat. See section 6.
• App update check. The app reads a public version policy (the latest version and whether an update is recommended) from Supabase. This is a standard HTTP request with no account or personal data in it; like any web server, the server sees request data such as your IP address. We do not store personal data from it.
• Groove packs. When you open Packs or download a pack, the app fetches the pack list and files from this website (Firebase Hosting). These are plain HTTP requests with no account or personal data; the hosting provider sees request data such as your IP address. Downloaded packs are stored on your device.
• MIDI controllers. If you connect a MIDI pad, the app reads its notes on your device to play strokes. Nothing about the controller or your playing is sent anywhere.

We do not link any of this to your name, email address or an account, because the app does not collect them.

Our website

This website does not use cookies, analytics or advertising scripts. It is hosted on Firebase Hosting, which keeps standard server logs (such as IP address, browser type and pages requested), and it loads fonts from Google Fonts, which receives your IP address. A language choice you make on the site is stored only in your browser.

2. Device permissions

Cajón Studio never asks for your camera, location or contacts. The Studio records the app’s own audio output, not the sound around you. A few permissions are requested only when you use the feature that needs them, and the app works without them:

• Internet — used for ads in the free version, purchases, the update check and, if you turn them on, diagnostics. Playing, lessons, grooves and recording work without a connection.
• App Tracking Transparency (iOS) — see section 5.
• Advertising ID (Android) — see section 5.
• Microphone (optional) — only if you turn on “Play my real cajón” in a lesson. The app listens while that lesson runs, detects when you hit the drum and which stroke it was, and scores your timing. This happens in real time on your device: the sound is not recorded, not stored and not sent anywhere, and the microphone is off as soon as you leave the lesson or turn the option off. You can withdraw the permission in your device settings at any time.
• Bluetooth (optional) — only to find and connect a Bluetooth MIDI drum pad when you choose “Connect Bluetooth MIDI pad”. The app looks only for MIDI devices and does not use Bluetooth to locate you. On Android 6–11 the system calls this permission “location”, because Bluetooth scanning requires it there; the app does not read your location. Bluetooth speakers and headphones are handled by your operating system and need no permission from the app.
• Photos / gallery (optional, add-only) — only when you save a screen recording to your photo library. The app can add the video; it cannot see or read your library.
• Screen recording (optional) — when you record a video of the app, your phone asks for permission (Android shows a system dialog and a notification while recording). The video contains only the app’s screen and the app’s own sound, not the microphone, and is saved on your device until you save or share it.
• Sharing — when you share a recording, your operating system’s share sheet handles it; the app does not need access to your files or other apps to do this.

3. How we use information

• To provide the app — to remember your settings, progress, grooves and recordings on your device, to check whether you have Pro or Remove ads, and to restore purchases.
• To keep the app up to date — to tell you when a newer version is available or recommended.
• To improve reliability and features — if you have turned on diagnostics, to find and fix crashes and to see in aggregate which features are used.
• To fund the free version — to show, measure and limit the frequency of ads, prevent ad fraud and, where you have agreed, show more relevant ads.
• To support you — to answer questions you send us, and to handle purchase and restore questions.
• To meet legal obligations — for example, keeping financial records.

Under the EU and UK GDPR, our legal bases are: your consent for diagnostics (given by turning them on and withdrawn by turning them off), for personalised advertising and for storing or accessing information on your device for advertising where consent is required; our legitimate interests in serving non-personalised ads that fund the free version, in checking for app updates and in keeping the app secure; performance of a contract for purchases and restores; and legal obligations for financial records.

We do not sell your personal information, and we do not use it for any purpose not described in this policy.

4. Diagnostics (opt-in)

Cajón Studio includes Google Firebase Analytics and Firebase Crashlytics. Both are off by default and only run on a device where you turn on Share diagnostics in Settings. You can turn it off again at any time, and no feature of the app depends on it.

While it is on, the app may send:

• anonymous usage events — for example, that a lesson was completed, a groove was played, or a purchase succeeded, failed or was cancelled — with basic device and app information (device model, operating system, app version, language and country) and a random app-instance identifier created by Firebase;
• crash reports — the error, the state of the app when it happened, and basic device and app information.

Diagnostics never include your recordings or the individual strokes you play.

5. Advertising and consent

The free version of Cajón Studio shows ads served by Google AdMob. Ads are never shown on the playing screen, during lessons or while you are recording. On the Pro screen you can choose to watch a short video ad that unlocks Pro for 15 minutes.

If you have Pro or Remove ads, the app shows no ads and makes no ad requests.

Consent

Before any ad is requested, the app uses Google’s User Messaging Platform to check whether a consent message is required where you are. In the EEA, the UK and Switzerland this message follows the IAB Transparency and Consent Framework (TCF) and lets you accept, refuse or choose specific purposes and partners. If you do not consent to personalised ads, you may still see non-personalised or limited ads, which use information only to serve, measure and protect ads.

You can review or change your choice at any time with Settings → Advertising privacy choices in the app.

Tracking on iOS (App Tracking Transparency)

On iOS, the app may ask your permission to track your activity across other companies’ apps and websites for advertising. It asks only after any required Google consent message has been completed. The device advertising identifier (IDFA) is only available if you allow tracking. Declining does not limit any feature of the app; you see non-personalised ads instead. You can change your choice at any time in Settings → Privacy & Security → Tracking.

Android advertising ID

On Android, the advertising ID is used for personalised ads only where you have consented; otherwise non-personalised ads are shown. You can reset or delete the advertising ID in your device settings (usually Settings → Privacy → Ads or Settings → Google → Ads).

Google acts as an independent controller of the advertising information it collects. See How Google uses information from sites or apps that use its services. We receive only aggregate reports from AdMob, such as impressions and earnings, not information about you individually.

6. Purchases

Cajón Studio offers two optional one-time in-app purchases, with no subscription and no renewal: Pro (lifetime) and Remove ads. They are sold through the Apple App Store and Google Play, which process the payment. We never receive your card number, billing address or other payment credentials.

We use RevenueCat to show the products and prices, confirm your entitlement, and restore purchases. RevenueCat identifies the app installation with an anonymous app user ID — not your name or email — and receives purchase information from the store (product, purchase date, price, currency, store country and entitlement status), basic device and app information, and your IP address. Restoring works through your App Store or Google Play account: sign in to the same store account and tap Restore purchases. We can see anonymous purchase records, which we use to support customers and keep financial records.

A 15-minute Pro pass unlocked by watching an ad is stored on your device only and is not a purchase.

7. Third-party services

Firebase, RevenueCat and Supabase process information on our behalf as processors, under data processing terms that require them to protect it. Google, when serving ads, and Apple and Google, as app stores, handle information under their own privacy policies.

8. International transfers

Our service providers — Google (including Firebase and AdMob), RevenueCat and Supabase — may process information outside your country, including in the United States. Where information from the EEA, the UK or Switzerland is transferred, they rely on legally recognised safeguards such as the European Commission’s Standard Contractual Clauses, the UK International Data Transfer Addendum, or an adequacy decision such as the EU–US Data Privacy Framework where the provider is certified.

9. Retention and security

• On your device: kept until you delete it in the app, delete the app, or clear its data.
• Diagnostics: kept for a limited period under Firebase’s retention settings, after which it is deleted or kept only in aggregate.
• Advertising information: kept by Google under Google’s retention policies.
• Purchase records: kept as long as needed to provide your purchases, restore them, handle refunds and meet tax and accounting obligations.
• Update check: nothing is stored by us; the hosting provider may keep short-lived standard server logs.
• Emails you send us: kept while we handle your request and for a reasonable period afterwards.

Information sent from the app is encrypted in transit. Information on your device is protected by your operating system’s app isolation and device security. No method of transmission or storage is completely secure, but we limit what is collected to reduce the risk.

10. Your choices and rights

Choices in the app

• Diagnostics: Settings → Share diagnostics is off by default; turn it on or off at any time.
• Ad consent: Settings → Advertising privacy choices.
• Tracking and advertising ID: your iOS Tracking setting or Android Ads setting (section 5).
• No ads at all: Pro or Remove ads stops ads and ad requests.
• On-device data: delete recordings and grooves in the app, reset progress in Settings, or delete the app (or clear its storage) to remove everything it stored on your device.

Your rights

Under the EU and UK GDPR and similar laws, you have the right to access, correct and delete your personal data, to receive a copy of it, to restrict or object to its processing, and to withdraw consent at any time without affecting processing before the withdrawal.

Most of your data never reaches us: it lives on your device, and deleting the app deletes it. For data held by our providers:

• Purchase records (RevenueCat): email us with the order or transaction ID from your Apple or Google receipt, so we can find the matching anonymous record.
• Diagnostics (Firebase): turn diagnostics off; to ask for deletion of data already sent, email us. Because it is tied only to a random identifier, we may need details such as the approximate date and device model to find it.
• Advertising data (Google): use your consent choices, your device’s ad settings and My Ad Center, or contact Google directly.

We will answer within one month. You also have the right to complain to your local data protection authority.

11. California and other US states

If you live in California or another US state with a consumer privacy law, you have the right to know what personal information we collect, to delete it, to correct it, and to opt out of its “sale” or “sharing” for cross-context behavioural advertising. We do not sell personal information for money. Personalised ads served by Google AdMob in the free version may count as “sharing” under these laws; you can opt out by declining personalised ads in Advertising privacy choices, by not allowing tracking on iOS, by deleting your advertising ID on Android, or by buying Pro or Remove ads. We will not discriminate against you for exercising these rights. To make a request, email us at the address below.

12. Children, changes and contact

Children

Cajón Studio is not directed at children under 13, and we do not knowingly collect personal information from them. In the EEA and the UK, where the age of digital consent is higher (up to 16), consent for diagnostics and personalised ads must be given or authorised by a parent or guardian for users below that age. If you believe a child has sent us personal information, contact us and we will delete it.

Changes to this policy

We will update this policy when the app or the services it uses change. We will change the date at the top of this page and, for material changes, tell you in the app or on this website before they take effect.

Contact us

For privacy questions or requests, contact DQCLabs, publisher of Cajón Studio, at cuong.software.dev@gmail.com.