1. Who we are
Nihontekini is run by Maksym Sai ("we"). This policy covers the Nihontekini iPhone app, its servers (including the MCP server that AI agents connect to) and this website. Questions go to help@nihontekini.app.
2. If you use Nihontekini as a guest
Without an account, your decks, cards, notes, review history and settings are stored in a database on your phone. We do not receive them. Deleting the app deletes them.
Some features still call our servers without an account, such as looking up a word in the dictionary or downloading a ready deck. Those requests carry the word or deck you asked for and your IP address, which we use for rate limits.
3. What we collect with an account
When you create an account we keep what sign-in, sync and your plan need:
- Your email address, or the identifier Apple or Google gives us when you sign in with them, and a display name.
- Your study profile: level, goals and the settings you choose in the app.
- Your decks, cards, notes, tags, review history and import batches, so they stay the same on every device.
- Agent connections you create: the client’s name, the permissions you gave, when it was created and last used, the access tokens that let it reach your decks, and the quizzes it made and your answers to them.
- Your plan: whether you have Plus, which product, when it renews or ends, and how much of the free monthly allowance you have used.
- A push notification token, if you turn on reminders or agent notifications.
5. What we collect automatically
Our servers record technical information to keep the service running: the time and route of each request, errors, response times, the app version and your IP address. We use IP addresses for rate limits and abuse prevention. There are no analytics or advertising SDKs in the app, and we do not track you across other apps or websites. This website sets no cookies.
6. Chatbots, imports and agents
Nihontekini does not send your text to any AI service. When you copy a prompt into a chatbot, that conversation happens in the chatbot you chose and follows its privacy policy.
When you paste an answer back, the app reads it on your phone. If you are signed in, the terms in it are sent to our servers to be matched against the dictionary.
An agent you connect over MCP (such as Claude or ChatGPT) can read and change your decks, see your progress and make quizzes only within the permissions you gave it. What the agent’s provider does with that data is covered by its own policy. You can revoke an agent at any time in the app.
7. The contact form
When you write to us through this website, we receive your message, the topic you picked, and the name and email you give. We use them only to answer you, and delete them once the conversation is over unless it is needed to keep a record of a problem or request.
8. How we use your data
We use your data to sign you in, sync your decks, fill in cards from the dictionary, run agent connections, apply your plan, send the notifications you asked for, prevent abuse and fix problems. We do not show ads, we do not sell personal data, and we do not use your decks to train AI models.
9. Who helps us run it
A small number of service providers process data on our behalf:
- Render, for our API servers and session cache.
- Neon, for our Postgres database.
- Vercel, for this website and its contact form.
- Resend, to email you sign-in codes and to deliver contact form messages.
- RevenueCat, to check App Store purchases.
- Apple, for Sign in with Apple, purchases and push notifications, and Google, if you sign in with Google.
10. How long we keep it
We keep your account data for as long as you have an account. Server logs are kept for up to 30 days. When you delete your account, your data is deleted from our database straight away and disappears from backups within 30 days.
11. Your choices and rights
You can export all your decks from the app (Me, then Data), correct anything in your profile, and delete your account (Me, then Account, then Delete account). Deleting your account also revokes every agent connection. Cancelling Plus is done in your Apple ID’s subscription settings. Depending on where you live, you may have further rights, such as access, correction, deletion, portability and objection, and the right to complain to a data protection authority. To use them, write to help@nihontekini.app.
12. Children
Nihontekini is not directed at children under 13. If you believe a child has given us personal data, contact us and we will delete it.
13. Security
We protect data in transit with encryption, limit who can access production systems, and keep agent access tokens short-lived and revocable. No system is perfectly secure, so please keep your devices and email account safe.
14. Changes and contact
If we change this policy in a way that matters, we will say so in the app before the change takes effect. The effective date at the top always shows the latest version. Questions: help@nihontekini.app.