Privacy Policy — Yukigo (beta)

Last updated: 6 August 2026

Data controller

In short

Yukigo is built local-first: your study data lives on your device and you can study offline. Your progress is also saved to an anonymous sync profile (a random identifier, with no name or email), so it doesn't get lost; linking an account is optional and lets you retrieve it on another device. When you ask Yuki (the AI tutor) a question, it is processed by our server to generate the answer. We show no ads and we never sell your data.

Data stored on your device

All study data (progress, reviews, streaks, statistics, settings) is stored locally on your phone. You can use the app without creating an account. So that it doesn't get lost, your study data is additionally synced to an anonymous profile hosted on our servers — see the next section.

Sync profile and optional account

So that your progress doesn't get lost, the app automatically creates an anonymous sync profile: a random identifier — with no name, email or anything else that identifies you — that your study progress (review/SRS state, XP, streak, level and settings) is associated with.

If you choose to link an account (via email, Apple or Google sign-in), for example to retrieve your progress on a new device, we additionally store:

your login identifier (your email address, or the identifier provided by Apple/Google);
the display name you choose.

This data is hosted on Supabase infrastructure and is used only to provide sync and the features below — never for advertising.

Leaderboards

If you take part in the weekly leagues, your display name, level, weekly XP and country (if set) are visible to the other participants of your league. You can pick any display name; until you set one, others simply see you as “Anonimo”.

Reminder notifications

Daily reminders (due reviews, streak at risk) are scheduled locally on your device. In addition, if you have granted the notification permission, the app registers a push notification token on our servers (Supabase) — a technical device identifier issued by the system's notification services — together with your app language and timezone, used only to send you reminders in your language at the right time of day: a nudge to pick your studies back up after a period of inactivity, the countdown to the exam date you set, and your weekly league result. Delivery goes through Expo and Google Firebase Cloud Messaging, acting purely as transport channels. You can turn reminders off at any time with the "Reminders" switch in the app settings or by revoking the system notification permission; the token is deleted when you delete your account. Never any advertising in notifications.

AI tutor (Yuki)

When you ask Yuki a question, the text of your question and the relevant lesson context are sent to our server and processed by an AI provider (Anthropic) to generate the answer. Questions are subject to a daily limit. We do not use your questions for advertising or profiling.

Pronunciation practice (microphone)

When you use the pronunciation exercises, your voice is recorded only while you hold/tap the record button. The recording is sent to Microsoft Azure AI Speech (servers in the EU, Ireland), which processes it on our behalf solely to produce the pronunciation evaluation. The audio is not stored: we never save it on our servers, the app deletes it from your device when you leave the exercise, and it is not retained by the service after processing. What we do keep: the score, the practiced phrase and the app language, linked to your account — used only to show your progress and apply daily usage limits. The microphone permission is optional; you can revoke it anytime in your system settings. See Microsoft's privacy statement for details.

Error reporting (crash reports)

If the app runs into an error or closes unexpectedly, we send a technical report to Sentry (Functional Software, Inc.), a crash-reporting service, with data residency in the European Union. The report contains technical data only: the type of error and where in the code it happened, the device model, the operating system version and the app version. It does not contain your IP address, your identity or your study content, and it is not linked to your account (if you have one). We use these reports only to fix defects in the app. See Sentry's privacy policy for details.

Usage statistics (analytics)

To understand which features are useful and where the app needs improving, we collect anonymous usage statistics via PostHog, on servers in the European Union. Events record what gets used (for example: lesson completed, review session finished, exam simulation started), not your study content or your identity: no name, email or account is attached. We use this data only to improve the app, never for advertising. See PostHog's privacy policy for details.

Newsletter (optional)

If you subscribe to the newsletter, we store your email address and the language of the site you signed up from, and use them only to update you about Yukigo (for example to let you know when the app launches). Signups are confirmed with double opt-in. Storage and sending are handled by Brevo, a European email service provider that processes the data on our behalf. You can unsubscribe at any time via the link in every email or by writing to support@yukigo.app; on unsubscribing, the address is removed.

Website (analytics)

This website (yukigo.app) uses Vercel Web Analytics: a cookieless, aggregate measurement of traffic (e.g. page views) that collects no personal data and does not track individual visitors. See Vercel's privacy policy. It also uses PostHog (servers in the European Union) to record, again without cookies, page views and a few anonymous events (for example, clicking the beta button): no personal data, no profiling of individual visitors. See PostHog's privacy policy.

Test phase (beta)

During the test, if you choose to send feedback, questionnaire answers or screenshots of your statistics, we will use them only to improve the app. It is voluntary: you are not required to send them.

Third-party services

The app is distributed via Apple TestFlight (iOS) and as an APK file (Android). Through TestFlight, Apple may collect technical data (e.g. crashes and device information) under Apple's privacy policy.
Supabase hosts accounts and synced data (see above).
Expo and Google Firebase Cloud Messaging deliver push notifications to devices (see above).
Anthropic processes AI tutor requests (see above).
Brevo handles newsletter signups and sending (see above).
PostHog receives anonymous usage statistics, on servers in the EU (see above).
Sentry receives the app's technical error reports, on servers in the EU (see above).
The app's Japanese voice audio files are generated with Microsoft Azure text-to-speech (EU servers) from the app's own teaching content — never from your data — and delivered as audio files; if an audio file isn't available, your device operating system's voice is used instead.
Microsoft Azure receives the pronunciation-exercise voice recordings (evaluation only, not retained) and generates the app's Japanese voices, on EU servers (see above).

No data sale

We do not sell or share your data with third parties for advertising purposes.

Your rights (GDPR)

You have the right of access, rectification, erasure and objection. To delete the data stored locally, it is enough to uninstall the app. To delete your sync profile (or account) and all synced data you can use the deletion option in the app's Settings, or write to support@yukigo.app and we will remove it. For any other request, use the same address.

Minors

Yukigo is not intended for children under 14. If you take part in the test and are a minor, do so with the consent of a parent or guardian.

Changes

We will update this policy whenever the way we handle data changes. The date at the top indicates the latest version.