Privacy

Privacy Policy

Mukashi is designed to work without accounts and to collect as little information as possible.

Last updated: July 2026

Overview

Mukashi does not require user accounts. This policy describes what data may be processed when you use the Mukashi website or the Mukashi Reader browser extension.

WaniKani API Key

If you choose to provide a WaniKani API key, Mukashi uses it only to retrieve your learning progress so it can generate level-appropriate stories. Your key is stored in your browser's local storage and is never sent to Mukashi's servers. Clearing your browser storage removes it entirely.

Browser Storage

Mukashi stores your WaniKani API key, vocabulary assignments, and subject data in your browser's local storage. This data stays on your device. Nothing is synced to or held by Mukashi.

Generated Content & AI Processing

Stories are generated using an AI service. To create a story, Mukashi sends a prompt that includes a set of vocabulary words derived from your learning progress. Your WaniKani API key and personal identifiers are never included in these prompts.

Mukashi Reader Browser Extension

The Mukashi Reader browser extension lets you look up Japanese words on any webpage. When you click a word, the extension sends a small window of surrounding text (up to 400 characters) and the click position to Mukashi's server for tokenization and dictionary lookup. No other page content is read or transmitted.

The extension never reads or sends text from password fields, text inputs, textareas, or content-editable areas.

A random, anonymous identifier is generated on first install and stored in your browser's extension storage. It is used only for per-install rate limiting and contains no personal information. Uninstalling the extension removes it.

Lookup results are cached locally in your browser's extension storage for up to 7 days to reduce repeat requests. This cache never leaves your device and can be cleared from the extension's options page at any time.

Analytics

Mukashi uses two analytics services to understand how the site is used: Vercel Analytics and PostHog.

Vercel Analytics collects anonymized page view and performance data. It sets no cookies and uses no persistent identifiers or cross-site tracking.

PostHog records product usage events (for example, when a story is generated, rated, or shared) and error reports. How it runs depends on your choice in the cookie consent banner:

If you decline (or haven't chosen yet): PostHog runs in memory-only mode. No cookies or browser storage are used, and no identifier survives beyond the page you're viewing. Events are anonymous and cannot be linked to you, your device, or your other visits.

If you accept: PostHog stores a random analytics identifier in a cookie and browser storage so we can understand usage across visits. This identifier is not your name or email, and we do not sell this data or use it for advertising.

You can change your choice at any time via the "Cookie Preferences" link in the footer. Withdrawing consent removes PostHog's cookie and stored identifiers. Analytics requests are routed through Mukashi's own domain (a path beginning with /ingest) and forwarded to PostHog's US servers; this is done for reliability, and the data handling is the same as described above.

Cookies

Mukashi sets the following cookies. Essential cookies are required for the site to function and are used regardless of consent; the analytics cookie is set only if you accept it.

Essential: authentication cookies from Clerk (only if you sign in), used to keep you signed in and secure your session; and mukashi_consent, which remembers your cookie choice for 12 months.

Analytics (optional, consent-based): a PostHog cookie containing a random analytics identifier, set only after you click Accept in the consent banner. No advertising, retargeting, or cross-site tracking cookies are used — by Mukashi or anyone else on the site.

Technical Data

Mukashi's hosting infrastructure may process standard request data (IP address, browser type, request logs) for reliability and security purposes.

Third-Party Services

Mukashi relies on Vercel (hosting and analytics), PostHog (product analytics), Clerk (authentication, if you sign in), an AI provider (story generation), and WaniKani (if you connect your account). Each operates under their own privacy policies.

Contact

Questions or concerns? Reach out at mukashistories@gmail.com.

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