Privacy policy

Who is responsible for your data

Kotojutsu's publisher, who runs it in a personal capacity, reachable at [email protected].

What is collected, and why

No sensitive data (health, opinions, etc.) is requested. No automated decision has a legal effect on you: the review algorithm only decides when to ask you a question again.

Audience measurement

To know how many people come to Kotojutsu, each page shown is counted by Kotojutsu itself, with no third-party service or cookie. Only the page address, the site you came from (for example "google"), the device type, its system (iOS, Android, Windows…), the country, and whether the visit comes from a signed-in member (yes or no, without saying who) are kept. In lessons, we also count how many people reach each card and each exercise, to see where lessons are abandoned: a simple counter per lesson, not linked to your account.

To count unique visitors in a day, your IP address and browser are turned into a fingerprint using a secret that changes every day and is then destroyed. The IP address is never stored, and the next day nobody can link the fingerprint to you anymore. Page views are never attached to your account.

This measurement meets the consent-exemption conditions set by the CNIL (the French data protection authority). You can still object: your browser is respected if it sends the "Global Privacy Control" or "Do Not Track" signal, and you can also turn it off here.

How long

• Account and progress: Until you delete it, or 3 years without any sign-in.
• Guest account never turned into an account: 30 days after the last visit.
• Detail of each answer: 2 years (the memory of each card stays as long as the account exists).
• Security log: 12 months.
• Card decks: Until you delete them, or with your account.
• Reports: 12 months after they are handled.
• Words suggested for the dictionary: As long as the dictionary exists (no longer linked to your account once it is deleted).
• Audience measurement: 13 months.
• Android app statistics: 13 months (detached from your account if it is deleted).
• Number of questions asked to Densha (without their text): 90 days.
• Practice tests started and never finished: 30 days.
• Sign-in sessions: 30 days at most.
• Password reset links: 30 minutes, single use.

Deletion happens automatically every day.

Who can access it

Only the publisher, as administrator, and only to run and secure the service. Your data is neither sold nor rented. These technical providers are involved:

• Cloudflare, Inc. routes the traffic and protects the site: it sees your IP address. It also forwards messages written to the contact address. Transfers to the United States are covered by the EU–US Data Privacy Framework and by the European Commission's standard contractual clauses.
• Mailjet (Sinch group) only sends password reset emails, at your request. Its servers are in the European Union. Its usual tracking is turned off for every email: no tracking pixel to know whether the message was opened, and the link goes straight to Kotojutsu, without going through its servers to count clicks.
• Google (Cloud Text-to-Speech) reads aloud the Japanese of the cards you write or import. Kotojutsu's server only sends it this Japanese text, with nothing that identifies you (no account, no IP address), then keeps the audio so it does not ask again.
• Google (sign in with Google) signs you in if you choose "Continue with Google", and only then. Kotojutsu asks it for your email address, verified by Google, and an account identifier: not your name, photo or contacts. Google then knows that you use Kotojutsu, under its own privacy rules. You can remove this link from your Google account; your Kotojutsu account stays, and you can add a password to it with "Forgot password".
• Groq, Inc. runs Densha's AI model, only when you ask it a question (see below). Its servers are in the United States; the transfer is covered by the European Commission's standard contractual clauses.

Fonts are served by the site itself: your browser contacts no third-party service. The Japanese voice of the course (Google or VOICEVOX, chosen in the settings) is recorded in advance and served by the site itself: listening to a sentence contacts no third-party service.

Data received from Google

If you choose "Continue with Google", Kotojutsu receives from Google your email address (verified by Google) and your Google account identifier. It asks for nothing else: not your name, photo or contacts, nor access to Gmail, Drive or any other service.

These two pieces of information are only used to create your account and sign you back in. The email address is encrypted in the database, as for a regular sign-up. They are never sold, shared, used for advertising or to train an AI. They are deleted with your account, at any time, from the settings.

Kotojutsu's use of information received from Google APIs complies with the Google API Services User Data Policy, including the Limited Use requirements.

Densha, the AI assistant

Densha answers members' questions about Japanese. When you write to it, Kotojutsu's server sends Groq your question, the last messages of the conversation and a summary of the open lesson or card. It does not send your username, email or IP address. Groq does not keep these exchanges by default, except, for up to 30 days, to investigate abuse.

Kotojutsu never stores the text of questions or answers: only, for each day, how many questions you asked and the amount of text processed. These counters enforce the daily limit and give the administrator overall statistics. They are deleted after 90 days, or with your account. The conversation itself stays in your browser tab and disappears when you close it.

Do not write personal information in your questions: Densha does not need it to help you.

Cookies

Kotojutsu only uses cookies that are essential for signing in: they are exempt from consent (article 82 of the French Data Protection Act). No audience-measurement, advertising or social-network cookie.

The trial uses a guest account: a username, with no email or password, kept on the server like a normal account. It follows you on this device only, until you create your (free) account, and it is deleted after 30 days without a visit. The "my progress" image is made in your browser: it only goes where you choose to share it.

• kj_at: Keep you signed in (access token) (15 minutes).
• kj_rt: Renew your session without asking for your password again (30 days).
• kj_session: Tell the page that a session exists, and whether it is a guest account (no data) (30 days).
• kj_google: Secure the round trip to Google when you choose to sign in with it (no data about you) (10 minutes).
• kj_theme: Show your theme (day, night…) from the first page, without flashing the light theme (1 year).
• kj_locale: Show the app in your account's language (French or English) from the first page (1 year).

Your browser also keeps, by itself, a few settings and memories of the app (local storage). They never leave your device, are not used to track you and, like the cookies above, are exempt from consent. You can erase them by clearing the site's data in your browser.

• kj_nostats: Your opt-out from audience measurement (until you change your mind).
• kj_visites: The guided tours already seen (dojo, flashcards…): they no longer open by themselves (permanent).
• kotojutsu:guide-ferme: The old welcome guide was closed: the dojo tour does not open by itself (permanent).
• kj-jp: The Japanese fonts are already downloaded: show them from the first frame (permanent).
• kj_app_iphone_vu: The tip on adding the site to your iPhone home screen has been seen (permanent).
• kj_app_android: Your answers to the Android app banner ("No thanks" or "Download"): so it is not offered again too soon (permanent).
• kj_flash_niveaux: The folded or unfolded levels of the Flashcards page (permanent).
• kotojutsu.flash.autoAudio: Automatic audio on cards, yes or no (permanent).
• kj_phrases: Your last choices for fill-in-the-blank sentences (level, type, mode) (permanent).
• kj_speed_pick: The last mode and level chosen in the speed test (permanent).
• kj_speed: The result of a speed test played without an account, until you create your account (24 hours).
• kj_exam_…: Your answers to a practice test started without an account, to resume it (until the end of the test).
• kj_provenance: The site through which you found Kotojutsu (for example reddit.com), counted anonymously if you create an account (permanent).
• kj_evt_invite_lecon: Your first trial lesson has already been counted in the audience measurement (permanent).

And, for the life of a tab only (erased when you close it):

• panel-…: Your conversation with Densha on the open page.
• kj_greeted: The little welcome train has already passed.
• kj_locale_reload: The page has just been reloaded to follow your account's language (not twice in a row).
• kj_app_android_vues: The number of pages viewed during the visit, so the Android app is only offered from the second one.
• kj_app_ping_…: In the Android app: its launch has already been counted for this session.
• kj_speed_done: The speed test result to show right after you sign up.
• kj_compte_cree: Show the welcome message right after the account is created.
• kj_google_trip: Know, when coming back from Google, whether you were signing in or adding Google to your account.

Security

Passwords hashed with Argon2id, encrypted email addresses, end-to-end encrypted connections (HTTPS), sessions you can revoke at any time, protection against bots without a third-party service, a daily database backup (kept 7 days), and logged administrator access. In case of a data breach presenting a risk, the CNIL is notified within 72 hours and the people concerned are informed.

Minors

Sign-up is open from the age of 15. Below that, a parent's or guardian's consent is required (article 45 of the French Data Protection Act).

Your rights

You can access your data, correct it, erase it, get a copy, restrict its use or object to it. Most of these rights can be exercised directly in your profile:

• Download my data: a complete, machine-readable file.
• Delete my account: immediate and permanent erasure of all your data.
• Appear on the leaderboard: turn it off whenever you like.

For anything else, write to [email protected]: answer within one month. If you think your rights are not respected, you can complain to the CNIL.