Effective date: October 11, 2026
This Privacy Policy explains what information the DUOL mobile game ("DUOL", "the App", "we") collects on iOS and Android, how it is used, and the choices you have. DUOL is developed by Aykhan Valiyev (Valiyev Games).
Your game progress (levels, stars, best times and moves), your in-game wallet (gems, hints, freezers) and your settings (sound, haptics, personalized ads) are stored only on your device. We do not run servers that receive or store this information. Deleting the App deletes this data.
We do not ask for, collect or store your name, email address, phone number, contacts, photos or precise location. The App has no accounts and no sign-in.
DUOL offers optional in-app purchases (gem packs and, on Android, the monthly Premium pass). Payments are processed entirely by Apple (App Store) or Google (Google Play). We never receive your payment card or billing details; the store only tells the App which product was bought so it can be delivered. See Apple's Privacy Policy and Google's Privacy Policy.
On Android, DUOL shows two kinds of ads: a short rewarded video when you choose to watch one, for example for a hint, a freezer, extra moves or free gems; and, now and then, a full-screen ad between levels. The App shows no other ads. The ads are served by Unity LevelPlay and its ad networks, Unity Ads and ironSource Ads (Unity Technologies and its affiliates).
To show these ads, measure them and prevent fraud, the ad partners receive from your device: your device's advertising ID and app set ID, your IP address and the approximate location derived from it, the device model, operating system, language and network type, the App's name and version, and how you interact with the ads (for example, whether a video was watched to the end or tapped). They do not receive your game progress.
The ad partners process this information as described in the Unity Game Player and App User Privacy Policy.
To learn which of our own advertising campaigns brought players to DUOL, and how those campaigns pay off, the Android app uses Tenjin, a measurement service (Tenjin, Inc.). Tenjin receives from your device: your device's advertising ID and app set ID, the Google Play install referrer, your IP address and the approximate country derived from it, the device model, operating system, language and network type, the App's version, when you open the App, the revenue of the ads shown to you, and the gem packs you buy (product, price and the store's purchase receipt, so Tenjin can check that the purchase is real). It does not receive your game progress.
Tenjin processes this information on our behalf. It may tell the ad network whose campaign brought you to DUOL (for example AppLovin) that you installed the App or bought a gem pack, so that network can measure its campaign. Where we ask for consent for personalized ads (the EU/EEA, the UK and Switzerland), Tenjin receives nothing until you agree, and turning "Personalized ads" off in Settings stops it. See Tenjin's privacy policy.
To find and fix bugs, the App uses Google Firebase Crashlytics. When the App crashes, Crashlytics may send a crash report containing technical information such as the device model, operating-system version, app version, the state of the App at the time of the crash and a random installation identifier. Crash reports do not contain your name or contact details. See Firebase privacy and security.