MasterKanji — Privacy notice privacy-2026-11-02-v14 · 2 November 2026 Who operates MasterKanji? MasterKanji is operated by Dean Tearse, a sole trader trading as MasterKanji. Write to Dean Tearse, 5 Brayford Square, London, E1 0SG, United Kingdom for business correspondence, complaints or cancellation. Email support@masterkanji.com (mailto:support@masterkanji.com). Dean Tearse is the controller of your personal information. ICO registration reference: pending confirmation. Your privacy This notice explains how MasterKanji uses and protects your information. Email support@masterkanji.com (mailto:support@masterkanji.com) for privacy requests or complaints. We do not sell your personal information. Your account and learning If you choose Continue with Google, Google provides your email address, verification information and a stable Google account identifier for sign-in. Your chosen MasterKanji username remains public; we do not use your Google name or photo as your profile. We request no Gmail, Drive or contacts access, and do not retain Google access or refresh tokens. Verified Gmail and Google Workspace addresses can skip our confirmation email; other addresses need an additional inbox check before first use. Temporary browser-bound sign-in details expire within 30 minutes (initial authorisation requests within ten minutes) and are removed by bounded maintenance. Google also processes sign-in information under its Privacy Policy (https://policies.google.com/privacy). The Google identifier is removed with your account. We use your email, unique username, password hash, verification status and security-token digests to operate and protect your account. We store your level, lessons and reviews, scheduling, study notes and synonyms, lesson goal, earned chapters and membership state. Personal API keys are stored as digests; a new full key is displayed once. We also record the policy version and time of account or checkout acceptance. We do not ask ordinary learners for a home address or full date of birth. We process account and study information to provide the service you request. Our lawful basis is performance of our agreement where you can enter into it. Where a younger learner cannot independently enter into that agreement, we rely on the carefully balanced legitimate interests of providing the requested, private educational service, with the same privacy protections for everyone. Requested study reminders and followed-conversation updates use those service interests, remain optional and contain no offers. If required account information is missing, we cannot operate the account. Security and moderation use our legitimate interests in preventing abuse and protecting users; you may object. We retain records needed for applicable legal obligations and handling claims only for the relevant purpose and period. Public community and personal integrations Your username, posts and replies are public and can be indexed by search engines. Your email, learning record and personal notes are private. Do not post identifying, sensitive or contact information about yourself or others, especially children. We store follows, reports, moderation actions and notifications to operate the community. Support messages contain the information you choose to send and our response. A script or AI provider given your personal API key can perform the study operations your account permits. Check that provider’s terms before sharing a key, and replace or revoke it in Settings when no longer needed. MasterKanji does not automatically send your learning history to an external AI service. Email and your choices Account verification, recovery, security and membership messages support your account and do not require marketing consent. Optional reminders, weekly summaries, followed-topic replies and level celebrations start off and require your active choice. Change them in Settings or use an unsubscribe link. Reminder time and timezone are saved for scheduling. News and offers have a separate unticked choice in Settings for people aged 16 or older, use consent, and are never required to learn. Selecting it declares that you meet that minimum age; we do not collect your birth date or claim to verify it. Withdraw it at any time without affecting study emails or your account. We record the wording/version and time of your choice. An older combined signup choice is not permission for this separate newsletter. Marketing campaigns remain disabled until their separate delivery checks are satisfied. Automated messages use no-reply@masterkanji.com with replies directed to support@masterkanji.com. We do not enable email open pixels or click tracking. Delivery records and suppression checks help avoid repeated sending to failed or complaining addresses. Withdrawing an optional choice stops later optional sends, including queued messages when checked for delivery. Installed app and device notifications You can install MasterKanji on supported desktops and phones. The app needs an internet connection. Its service worker stores only a public offline page and install icons, not your account pages, lessons or API responses. Updates do not automatically interrupt an open lesson or game. App notifications require your browser’s permission and enabling a device in Settings. Review reminders, community updates and news/offers have separate choices from email. News and offers require a separate, unticked consent choice confirming you are 16 or older. You can withdraw it in Settings at any time. No advertising network is involved. We use current membership status to send relevant offers to the audience selected by the owner; we do not use browsing profiles or location tracking. We store a device label, push endpoint and encryption information, the associated sign-in session, preferences, reminder timezone/hour, consent wording/version and time, and delivery status. Your browser’s push service (for example Google, Apple, Mozilla or Microsoft) carries encrypted messages and processes connection and routing information under its own terms, which may involve international processing. Notifications may appear on a lock screen; community notifications do not include post text. Delivery acceptance is not proof that a notification was displayed or read. Sign-out, session expiry or revocation disables that session’s devices; enable the device again after signing in. Removing a device or deleting your account removes its push endpoint. Optional queued deliveries are checked again before sending. Delivery records are retained for up to 90 days and campaign records for up to 180 days through bounded maintenance. Device notification settings and delivery records are included in your account export. A notification already passed to a browser service cannot be recalled. Payments Stripe Managed Payments and Sold through Link provide hosted checkout and merchant-of-record transaction services. We send Stripe your account email and a purchase reference. Stripe collects payment and billing information, including the billing address. MasterKanji stores provider references, plan, billing country, currency, amount, payment and entitlement events; it does not store complete card numbers or security codes. Stripe/Link also uses information for its own transaction, fraud-prevention, regulatory and merchant-of-record purposes as described in the Stripe privacy policy (https://stripe.com/privacy). Deleting a MasterKanji account does not automatically erase financial records Stripe must retain. Hosting, email and international processing OVHcloud hosts the application database and files. Cloudflare provides DNS, proxy and traffic protection and can process network identifiers, request information and security events. SMTP2GO delivers app mail using its EU API endpoint and processes recipient addresses, message content and delivery/suppression information. Support mail is held on the operator’s Stalwart server with Roundcube webmail. Access is restricted to the operator and authorised service providers. These arrangements do not mean all provider processing or support access is confined to one country. Providers and their subprocessors may process information internationally under their applicable processing terms and transfer arrangements. These include adequacy arrangements for covered transfers and standard contractual clauses with UK provisions where required. Cloudflare and Stripe incorporate processing terms into their agreements; OVHcloud’s standard UK contract includes its data-processing agreement, and our SMTP2GO account has accepted its agreement including EU clauses and the UK Addendum. An EU sending endpoint alone does not mean all processing stays in the EU. Contact support for information or a copy of the safeguards relevant to your data. External dictionary/example links take you to separate sites with their own policies. Browser-generated pronunciation uses the speech service available on your device, which may use the device or browser provider’s processing arrangements. Personal flashcards We store your private flashcard decks, text and review schedules to provide study and export tools. While paid access is active, your personal API key lets tools you authorise read and review your own cards. You can export or delete this information. After paid access expires, extra decks are locked for a 30-day export and selection period. Choosing your one free deck permanently deletes the others, their review history. If you do not choose by the deadline, we retain the most recently studied deck (or the oldest if none has been studied) and delete the others. We send a service email about the deadline. Account deletion removes all personal flashcards; restricted backups expire separately as described below. Cookies and browser storage The first-party mk_session cookie supports secure sign-in. Anonymous security cookies expire after one hour; signed-in sessions expire after 14 days. The private preview additionally uses an access cookie lasting up to one day. Session storage can keep a review or lesson draft in your browser tab. Local storage remembers requested kana-practice choices/results, pricing currency and checkout country until cleared. Clearing browser storage removes those saved preferences. No advertising, third-party analytics, tracking pixels or remote fonts are included in the application. Stripe’s separate hosted checkout and Cloudflare’s security services have their own storage and privacy arrangements. Retention and deletion We keep your learning record and account preferences while your account exists, unless you delete them or another stated lawful retention need applies. Anonymous security cookies expire after one hour and signed-in sessions after 14 days, reset links after one hour and verification links after 24 hours. Signup request details, including your submitted password hash, email and choices, support safe resending and email correction for up to 24 hours. Browser-bound request records expire after 24 hours and are removed on confirmation or maintenance cleanup; confirmation links retain their own expiry. Confirmation can sign you in when the originating browser still holds its security context; otherwise you sign in with your password. Maintenance removes expired sessions/tokens and local-review outbox links older than 24 hours. In-app notifications and resolved moderation reports are removed after 90 days; unresolved reports remain while being handled. Restricted staff action records retain the acting account reference, action, target, time and minimal state for up to 180 days, with bounded maintenance cleanup; deleting an actor account removes its direct account link. Delivery content is cleared after delivery/cancellation, with delivery metadata normally retained up to 30 days. Hashed-address suppression records can remain to honour complaints and prevent repeated failed delivery. Providers have their own legal and operational retention rules. Deleting your account invalidates its access and removes private study information, preferences, acceptance history and authored community text from the active application. Other people’s replies and thread structure may remain with removal placeholders. Existing recurring Stripe subscriptions are cancelled before local deletion completes; if that provider step fails, deletion stops so a subscription is not silently orphaned. A deletion request is not automatically a refund request. To protect sign-in and staff authentication, we keep short security-event logs containing the visitor IP address, time and a fixed failure category. They do not contain submitted emails, passwords, authentication codes, API keys or request bodies. These restricted logs are capped in size, rotate daily or when full, and are removed within seven days. Repeated credential failures or clear exploit probes can cause a temporary IP block at Cloudflare, normally lasting 15 minutes; people sharing an internet address can be affected together. Contact support if you are incorrectly blocked. Stopped-app backups can retain older data until separately expired; deleting active data does not instantly erase a backup. We restrict backup access, review local copies for expiry after 28 days and retain an older copy only where needed for a documented recovery or legal reason. Before restoring service, we must replay deletions and withdrawn choices. Search-engine caches, screenshots or another person’s quotation are outside our direct control. We do not promise immediate deletion from every copy or an off-site backup service. Your rights and contact Settings provides profile correction, optional-email choices, data export, API-key revocation and account deletion. You can also email support to request access, correction, erasure, restriction or portability, object to legitimate-interest processing, withdraw consent or complain. These rights depend on the processing and applicable law. We verify requests proportionately and normally respond within one month, explaining any lawful extension or refusal. A payer or parent is not automatically entitled to another person’s private records; we check authority and the learner’s rights. You may complain to the UK Information Commissioner’s Office (https://ico.org.uk/make-a-complaint/) or the relevant authority where you live. Review scheduling uses answers to plan study; it is not a decision with legal or similarly significant effects. We do not use advertising profiles or location tracking. Younger learners You must be at least 13 to have an account. Public kana charts and account-free practice remain available without signing up. We do not ask for a birth date or use age-estimation technology: the same private study records, minimal data collection and optional-email defaults protect everyone. We do not use advertising profiles, public progress rankings, private messaging or user image/video uploads. Keep your password private and avoid putting your real name, school, location or contact details in public posts. You can report a discussion or email support@masterkanji.com for help, even without an account. A parent or trusted adult can help with a concern, but a payer does not automatically get access to your private learning record. If we learn that an account holder is under 13, we restrict the account, stop optional emails and arrange removal of the information, subject to any necessary safety or legal records. We check authority before sharing information and do not routinely ask for identity documents. A card payment or Terms checkbox is not verified age or parental permission. Changes and a copy for you We update this notice when processing changes and explain material changes through an appropriate account notice. You can save or print this page or download the notice (/policies/privacy-2026-11-02-v14.txt). Version: privacy-2026-11-02-v14. Updated 2 November 2026.