Terms of Use

Version 1.0 · Effective 14 October 2026 · Last updated 14 October 2026

These terms (the “Agreement”) are between you and DQCLabs (“we”, “us”), the publisher of the Cajón Studio app for iOS and Android and of the website virtual-cajon.web.app — together, “the app”. By downloading or using the app you accept this Agreement. If you do not accept it, please do not use the app.

1. Who may use Cajón Studio

You must be at least 13 years old to accept this Agreement yourself. If you are younger than that — or younger than the age of digital consent in your country (up to 16 in the EEA and the UK) — a parent or guardian must accept it for you and is responsible for your use of the app and for any purchase made with their store account.

The app has no accounts, no chat and no content shared with other users. It is not directed at children: the free version shows advertising (see section 10).

2. The licence we grant you

We grant you a personal, worldwide, revocable, non-exclusive, non-transferable licence to install and use Cajón Studio on devices you own or control, for your personal use, subject to this Agreement and to the rules of the store you obtained it from. This is a licence to use the app, not a sale of it. We keep every right not expressly granted.

3. Acceptable use

You agree not to:

• copy, sell, rent, lease, sublicense or otherwise distribute the app, or offer it on any other store or download site;
• reverse engineer, decompile or disassemble the app, except to the extent applicable law does not allow this restriction;
• remove, obscure or alter any copyright, licence or attribution notice in the app;
• interfere with the app’s operation or circumvent any limitation in it — including the purchase check or the time limit of a rewarded Pro pass — or modify the app to unlock Pro or remove ads without a valid purchase;
• generate fake ad impressions or clicks, or interact with ads by automated means;
• use the app for any unlawful purpose, or in a way that infringes anyone’s rights.

4. Your recordings and grooves

What you make is yours. We claim no rights in the recordings, videos and grooves you create with Cajón Studio, and you owe us no fee, credit or licence for them. You may publish them, commercially or otherwise. A credit is welcome and never required.

You remain responsible for the rights in any music you play along to or combine with your recordings. Being able to play along to a song does not give you a licence to publish someone else’s recording or composition.

5. Sounds, grooves and lessons we bundle

• Cajón sounds. The cajón samples come from the FreePats World Percussion collection, released under CC0 1.0 Universal (public domain dedication). Pro kit voicings are tone presets of these same recordings, not separate instruments.
• Guitar sounds. The nylon guitar backing uses recorded Spanish classical guitar samples from FreePats, released under CC0 1.0.
• Grooves and lessons. The groove patterns and lesson content are original works by us, also dedicated to the public domain under CC0 1.0. Groove names describe a musical feel; patterns described as flamenco-flavoured are not presented as traditional flamenco compás.
• Font. The interface uses the Inter typeface, licensed under the SIL Open Font License 1.1.

Licence notices for these and for the open-source software in the app are shown inside the app. If you believe something in the app is not ours to distribute, tell us at the address in section 22 and we will investigate and, if needed, remove it.

6. Our intellectual property

Apart from the CC0 and openly licensed material in section 5, the app’s name, logo, artwork, interface design, kit voicings, audio engine and code are owned by us or our licensors and are protected by copyright and other laws. This Agreement gives you no right to use our name or branding except to refer to the app accurately.

7. Your device and your data

Cajón Studio has no accounts. Your settings, lesson progress, grooves and recordings are stored on your device, inside the app, and nowhere else. We have no copy and cannot recover them. If you delete the app, clear its storage, reset or lose your device, that data is gone. Nothing syncs between devices. Export recordings you want to keep.

Your purchases are the exception: they belong to your App Store or Google Play account and can be restored (section 11).

How the app handles data — including opt-in diagnostics, advertising and purchase information — is described in our Privacy Policy.

8. Audio, latency and touch

Audio latency depends on your device, its operating system, your latency setting and any Bluetooth audio accessory you use, and is partly outside our control. Bluetooth headphones and speakers add delay that no app can remove. Phone screens cannot measure how hard you strike; touch dynamics approximate it from the size of your finger contact where the device reports it. Lesson timing feedback depends on calibration and is a practice aid, not a certified measurement.

9. Safe listening

Do not use the app while driving, cycling or doing anything else that needs your attention.

10. The free version and advertising

Cajón Studio is free to download. The free version includes the Flamenco Starter kit, the metronome, recording and sharing, the eight Foundations lessons and five grooves, and is funded by advertising.

• Third-party ads. Ads are served by Google AdMob. We do not choose individual ads and are not responsible for the content of third-party advertisements or for any product or site an ad leads to.
• Where they appear. Never on the playing screen, during lessons or while recording.
• Consent. Where the law requires it, the app asks for your consent before any ad is requested, and on iOS asks permission before your advertising identifier can be used. You can change your choices in Settings → Advertising privacy choices. Details are in the Privacy Policy.
• Rewarded Pro pass. You may choose to watch a short video ad on the Pro screen to unlock Pro for 15 minutes. The pass is granted only when the ad reports that it was watched; it is a free promotional benefit, has no monetary value, cannot be exchanged, transferred or restored, and is not a purchase. Its availability depends on ad inventory and your consent choices.
• Ad-free. Pro and Remove ads switch ads off, and the app then makes no ad requests.

11. In-app purchases

Cajón Studio offers two optional one-time, non-consumable in-app purchases. Neither is a subscription, and neither renews or charges again.

• Pro (lifetime) unlocks the Pro features described in the app at the time of purchase — currently three more kit voicings, seven more grooves and the Beat Designer, 18 more lessons and the studio tools — and removes ads.
• Remove ads removes ads only.
• Price and payment. The store shows the local price before you confirm and charges your Apple or Google Play account once. We never receive your payment credentials.
• Restoring. Use Restore purchases in Settings or on the Pro screen after reinstalling or on another device signed in to the same store account. App Store purchases restore on Apple devices and Google Play purchases on Android devices; purchases do not transfer between the two stores.
• Refunds. Payments are taken by Apple or Google, and refunds are handled by them under their own policies — request one through Apple (reportaproblem.apple.com) or Google Play. A refunded or revoked purchase loses its access. This does not affect your statutory rights.

12. EU and UK consumers: right of withdrawal

If you are a consumer in the EU or the UK, you normally have a right to withdraw from a contract for digital content within 14 days without giving a reason. For digital content that is not supplied on a physical medium, that right ends once supply has begun with your express prior consent and your acknowledgement that you thereby lose the right of withdrawal.

Pro and Remove ads are supplied immediately after purchase. By confirming the purchase in the store, you request and consent to immediate supply and acknowledge that you lose your right of withdrawal once the content has been unlocked. This does not affect the refund policies of Apple or Google, which may be more generous, or your statutory rights if the content is faulty or not as described.

13. Availability, updates and changes

We may add, change or remove features, kits, grooves or lessons; require an update to keep using the app; or stop distributing it. We will not remove the core of what a valid Pro or Remove ads purchase provides — the Pro features in place when you bought it, and an ad-free app — while we continue to offer the app.

Playing, lessons, grooves and recording work offline. Ads, purchases and restores need an internet connection.

We may change this Agreement. If a change is material we will tell you in the app or on this site before it takes effect; continuing to use the app after that date means you accept it.

14. Termination

You may end this Agreement at any time by deleting the app. We may end it, and your licence with it, if you materially breach it — for example by tampering with the app to unlock Pro or by committing ad fraud. Deleting the app does not remove your purchases from your store account; a valid purchase can be restored as described in section 11. Sections that by their nature should survive termination do.

15. Disclaimer

To the fullest extent permitted by law, the app is provided “as is” and “as available”, without warranty of any kind, express or implied, including implied warranties of merchantability, fitness for a particular purpose and non-infringement. We do not warrant that the app will be uninterrupted, error-free, compatible with every device or suitable for live performance. Nothing here excludes a warranty or right that cannot be excluded under the law that applies to you as a consumer.

16. Limitation of liability

To the fullest extent permitted by law, we are not liable for any indirect, incidental, special, consequential or punitive damages, or for any loss of data (including recordings), profits, revenue or goodwill, arising out of or connected with your use of the app. Our total liability is limited to the greater of (a) the amount you paid us for in-app purchases in the twelve months before the claim and (b) USD 50.

Nothing in this Agreement limits our liability for death or personal injury caused by our negligence, for fraud, or for anything else that cannot be limited by law, and nothing limits your mandatory rights as a consumer.

17. Third-party services

The app relies on services governed by their providers’ own terms: the Apple App Store and Google Play (distribution, payment and refunds), RevenueCat (purchase status and restore), Google AdMob and Google’s User Messaging Platform (ads and consent for free users), Firebase Analytics and Crashlytics (only if you turn on Share diagnostics) and Supabase (the app update check). If one is unavailable, the parts of the app that depend on it may not work for that time.

18. Governing law and disputes

This Agreement is governed by the laws of Viet Nam, without regard to its conflict-of-laws rules, and the courts of Viet Nam have jurisdiction over any dispute. If you are a consumer, this choice of law does not deprive you of the protection of the mandatory consumer-protection rules of the country where you live, and you may also bring proceedings in the courts there. Please email us first — most problems are solved faster that way.

19. Apple App Store terms

Where you obtained the app from the Apple App Store, the following applies and prevails over anything inconsistent above:

• This Agreement is between you and us only, not with Apple. We, not Apple, are solely responsible for Cajón Studio and its content.
• Your licence is limited to using the app on Apple-branded products you own or control, as permitted by the Usage Rules in the Apple Media Services Terms and Conditions.
• Apple has no obligation to provide maintenance or support for the app.
• If the app fails to conform to any applicable warranty, you may notify Apple and Apple will refund the purchase price, if any. To the maximum extent permitted by law, Apple has no other warranty obligation with respect to the app.
• We, not Apple, are responsible for addressing any claim relating to the app, including product liability claims, claims that it fails to conform to a legal or regulatory requirement, and claims under consumer protection or similar legislation.
• We, not Apple, are responsible for the investigation, defence, settlement and discharge of any third-party claim that the app infringes that party’s intellectual property rights.
• You represent that you are not located in a country subject to a US Government embargo or designated as a “terrorist supporting” country, and that you are not on any US Government list of prohibited or restricted parties.
• Apple and its subsidiaries are third-party beneficiaries of this Agreement and may enforce it against you.

20. Google Play terms

Where you obtained the app from Google Play, this Agreement is between you and us only. Google is not a party to it and is not responsible for Cajón Studio. The Google Play Terms of Service apply to your download and to any purchase made there, and Google’s refund policy governs any refund.

21. General

• Entire agreement. This Agreement and the Privacy Policy are the whole agreement between us about Cajón Studio.
• Severability. If a provision is held unenforceable, the rest stays in force.
• No waiver. Not enforcing a right straight away is not a waiver of it.
• Assignment. You may not assign this Agreement. We may assign it as part of a merger, acquisition or sale of assets, on notice to you.
• Standard EULA. This Agreement is the end-user licence agreement for Cajón Studio. Where you obtained the app from the Apple App Store and this Agreement is silent on a matter, Apple’s Licensed Application End User License Agreement applies to it.
• Language. This Agreement is written in English. Any translation is provided for convenience only; the English text prevails.

22. Contact

DQCLabs, publisher of Cajón Studio — cuong.software.dev@gmail.com