Koboshi

Legal

Privacy Policy

Koboshi is a place to keep the words you are learning. This policy explains, in plain terms, what we collect, why, who processes it, and the control you have over it.

Last updated: 29 June 2026

1. Overview

We collect the minimum we need to run the service and help you remember vocabulary. We do not sell your personal data, and we do not use your private journal content for advertising or for training third-party AI models.

2. Information we collect

  • Account information — your email address, and basic profile information (such as a display name) provided when you sign in with Google or an email magic link.
  • Onboarding preferences — the languages you know and are learning, your self-reported level, and similar study settings you choose.
  • Study content — the words you look up and save, meanings, notes, your review history and scheduling state, and any journal entries you create.
  • Usage events — in-app actions (such as lookups and reviews) used to operate features, measure quotas, and improve the product.
  • Device and technical data — information your browser sends automatically, such as IP address, browser/device type, and timestamps, used for security, abuse prevention, and diagnostics.

3. How we use your information

  • to provide the core service — lookups, saving words, and scheduling reviews;
  • to authenticate you and keep your account secure;
  • to enforce fair-use limits and detect or prevent abuse and fraud;
  • to maintain, debug, and improve the service;
  • to communicate with you about the service (for example, important account or service notices);
  • to comply with legal obligations.

4. AI processing of your words

When you look up a word, the word and the languages involved are sent to our AI provider (Anthropic) to generate a translation, meaning, and examples. To save cost and speed things up, common lookups are cached and shared so that the same word does not need to be generated again. We send only what is needed for the lookup — not your identity or your wider study history — to the AI provider, and we do not permit it to use your data to train its models.

5. Service providers

We rely on a small set of trusted providers to run Koboshi. They process data only on our behalf and under their own security and privacy commitments:

  • Supabase — database, authentication, and storage;
  • Anthropic — AI language model for word lookups;
  • Google Cloud — text-to-speech (pronunciation audio);
  • Vercel — application hosting and delivery.

These providers may process and store data in countries outside your own, as described below.

6. Cookies and local storage

We use cookies and your browser’s local storage to keep you signed in, remember your settings, and allow the app to work offline-style on your device. These are essential to the service. We do not use third-party advertising cookies.

7. How long we keep data

We keep your account and study data for as long as your account is active. If you delete your account, we delete or anonymise your personal data within a reasonable period, except where we must keep certain records to meet legal, security, or accounting obligations. Shared, anonymous lookup data in our cache (which is not tied to your identity) may be retained to keep the service fast for everyone.

8. Your rights

Depending on where you live, you may have the right to access, correct, export, or delete your personal data, to object to or restrict certain processing, and to withdraw consent. You can review and edit much of your data directly in the app, and you can request deletion of your account. To exercise any of these rights, contact us at 〔support@koboshi.app — to be confirmed〕. If you are in the EU/UK or Japan, you also have the right to complain to your local data-protection authority.

9. Data security

We use industry-standard measures to protect your data, including encrypted connections and per-user access controls so that you can only see your own data. No method of transmission or storage is perfectly secure, but we work to protect your information and to limit who can access it.

10. International data transfers

Because we use global cloud providers, your data may be processed in countries other than your own, which may have different data-protection laws. Where required, we rely on appropriate safeguards for such transfers.

11. Children’s privacy

Koboshi is not directed to children under the age described in ourTerms of Service. We do not knowingly collect personal data from children below that age. If you believe a child has provided us with personal data, contact us and we will delete it.

12. Journals and sensitive content

Any private journal or personal-notes content you create is treated as your private content. We do not sell it and we do not include it in any research or commercial dataset. It is used only to provide the feature to you.

13. Changes to this policy

We may update this policy from time to time. When we make material changes, we will update the “Last updated” date and, where appropriate, notify you in the app.

14. Contact

For privacy questions or requests, contact us at 〔support@koboshi.app — to be confirmed〕.