Privacy Policy

Nihongo Circle is a free Japanese-study website operated by an individual. For privacy questions, message @meltenx on X. For this data, we act as the data controller; the providers listed below act as our processors.

• Account information — handled by our authentication provider, Clerk: your email address, name, profile image, and any social-login identifiers you choose to connect.
• Profile — a public handle, display name, optional bio, and avatar.
• Learning data — your review schedule and history, challenge scores, daily activity and XP, streaks, badges, quests, and study preferences (such as your target exam date and chosen JLPT level).
• Preferences — theme, skin, audio voice and speed, and similar settings, stored in your browser’s local storage and/or your account.
• Content you submit — bug reports, suggestions, and friend requests.
• Audio text — when audio is generated, the Japanese text to be spoken is sent to our text-to-speech provider (Microsoft Azure) and the resulting audio file is cached. We don’t send your personal information for this.
• Missed answers, when you ask for an explanation — pressing “Why is that?” after a wrong answer sends the word, its meaning and example, and what you typed, to our AI provider so it can explain the difference. Your name, email and account ID are not sent — the request carries the word and the answer, nothing that identifies you. The resulting explanation is cached against that word and answer and reused for anyone who makes the same mistake, so a common wrong answer is only ever explained once.
• Technical & usage data — standard server logs (including IP address and browser/device info, processed by our hosting providers) and product analytics (pages visited and feature events such as completing onboarding, processed by PostHog on our behalf). We also keep a per-account daily count of audio generations to prevent abuse.

• Provide the Service and your account, and schedule your reviews.
• Show your progress, streaks, badges, and — if you take part — leaderboards.
• Generate and cache pronunciation audio.
• Respond to your reports and improve the Service.
• Keep the Service secure, prevent abuse, and enforce rate limits.

We rely on your consent and our legitimate interest in running the Service, and on performing our agreement with you (these are the legal bases where laws such as the GDPR apply).

We don’t sell your personal data. We share it only with service providers who process it on our behalf to run the Service:

• Clerk — authentication and account management.
• Supabase — database and storage for your account and learning data.
• Vercel — application hosting and aggregate, privacy-friendly analytics.
• PostHog — product analytics (how features are used), so we can improve the Service. Used for our own product decisions only.
• Microsoft Azure — text-to-speech generation.
• Vercel AI Gateway — routes explanation requests to the model that writes them (MiniMax M3, served by GMICloud). Sent only when you ask for an explanation, and only the word and the answer you gave.
• Cloudflare R2 — storage of generated audio files.
• RevenueCat — subscription billing, if you choose to subscribe to Pro. They and their payment partners handle payment details; we never receive or store your card number.

We may also disclose data if required by law or to protect the Service’s and users’ rights and safety.

Your handle, profile, and progress can appear on your public profile page and on leaderboards. You can hide yourself from the global leaderboard in Settings. Friend connections are visible to the people involved.

We use three kinds of browser storage:

• Necessary — cookies that keep you signed in (set by Clerk), and local storage for preferences like theme, skin and audio settings. These can’t be turned off without breaking the Service.
• Analytics — first-party PostHog storage (a cookie plus local storage) that tells us which features are used. In the EEA, UK and Switzerland we ask before loading this, and it stays off until you say yes. Everywhere else it’s on by default and you can switch it off in Settings → Privacy. Switching it off also clears what was already stored in your browser.
• Advertising — see the next section.

Nihongo Circle is free to use and always will be — no feature is ever locked behind payment. Advertising is how that gets paid for. An optional Pro subscription removes ads; it doesn’t unlock anything, because nothing is locked.

Today, the only ads we show are our own. They are plain links to other parts of this site. They set no cookies, load nothing from third parties, and involve no tracking or profiling whatsoever.

If we ever introduce a third-party ad network, we will update this policy and name the provider before the first ad appears, and — where consent is required — ask for it first. We will never sell your personal data, and we will never share your learning data with advertisers.

Ads never appear inside a review session or a timed round. They only appear on reference pages and at the end of a game.

We keep your account and learning data for as long as your account is active. If you delete your account, we delete the associated data, except where we need to keep limited records to comply with law or resolve disputes. Cached audio is keyed to the text spoken, not to you.

Depending on where you live, you may have the right to access, correct, export, or delete your personal data, and to object to or restrict certain processing. You can edit much of your profile and preferences in-app, and you can request the rest by messaging @meltenx on X.

You can withdraw consent for analytics at any time in Settings → Privacy— it’s one switch, exactly as easy as turning it on was.

The Service isn’t directed to children under 13, and we don’t knowingly collect their data. If you believe a child has given us personal data, contact us and we’ll remove it.

Our providers may process data in countries other than yours, including the United States. Where required, we rely on appropriate safeguards for those transfers.

We take reasonable measures to protect your data — see our Security Policy. If we change this policy, we’ll update the “Last updated” date above and note material changes in-app where practical.