Website Privacy Policy

Last updated: February 11, 2026

Overview

This privacy policy applies to the Yomi Sensei website (yomisensei.net) and its associated backend services. Yomi Sensei helps you track and improve your Japanese reading level. This policy explains what data we collect, how we use it, and your rights regarding that data.

For the privacy policy covering the Yomi Sensei browser extension, please see the extension privacy policy.

Data We Collect

Account Data

When you create an account, we generate a unique user ID. Accounts are anonymous by default. You may optionally provide:

  • Email address — used for password resets and account recovery.
  • Password — securely hashed and never stored in plaintext.

Reading Data

When you use Yomi Sensei (via the browser extension), your reading data is sent to our servers. This includes:

  • Sentences you read in Japanese, along with timestamps.
  • Word lookups — which words within a sentence you looked up.

This data is used to estimate your reading ability and provide personalized recommendations.

Derived Analytics

From your reading data, we compute:

  • A proficiency score based on Item Response Theory (IRT) models.
  • Estimates of your JLPT level probability distribution.
  • A set of words you have encountered.
  • Daily ability history snapshots.

Payment Data

If you subscribe to a premium plan, payment is processed entirely by Stripe. We store:

  • Your Stripe customer ID and subscription ID.
  • Your subscription tier and renewal/cancellation status.

We never see or store your credit card number, billing address, or other payment details — Stripe handles that directly.

Analytics Data

We collect anonymous usage analytics to understand how visitors use our website. This includes:

  • Page views — which pages you visit on yomisensei.net.
  • Device and browser information — such as browser type, operating system, and screen size.
  • Referral source — how you arrived at the website.
  • Session data — how you interact with the site during a visit.

If you are logged in, your anonymous user ID is linked to your analytics data so we can better understand how our users interact with the product. No personal information (such as your email address) is included in analytics data.

Cookies

When you log in, we set cookies to keep you authenticated. We also set cookies to distinguish unique visitors and track sessions for analytics purposes. We do not use any advertising cookies.

Data We Do NOT Collect

  • IP addresses
  • Precise location data
  • Browsing history — we only receive sentences you actively read through the extension. Analytics only track pages within yomisensei.net.
  • We use no advertising trackers or social media integrations.

How We Use Your Data

All collected data is used for the following purposes:

  1. Reading level estimation — calculating your Japanese proficiency from reading activity.
  2. Personalized recommendations — suggesting content at an appropriate difficulty.
  3. Progress tracking — showing your ability over time.
  4. Account management — authentication and access control.
  5. Subscription management — managing premium feature access via Stripe.
  6. Transactional emails — password resets and email verification (if you provide an email).
  7. Product analytics — understanding how the website is used so we can improve the experience.

Third-Party Services

We use the following third-party services:

  • Stripe — processes payments on our behalf. Your user ID is included in payment metadata; payment details (card number, billing address) are collected directly by Stripe and never reach our servers.
  • Email provider — delivers transactional emails (password resets, email verification). Your email address is shared only if you provided one.

We also query third-party public APIs to fetch content metadata (novel titles, descriptions, etc.). No user data is sent to these services.

Data Storage

Your data is stored on our servers. Data is retained indefinitely unless you request deletion.

Data Sharing

We do not sell, rent, or share your data with third parties for advertising or marketing purposes. Data is shared only with Stripe for payment processing and our email provider for transactional emails, as described above.

Data Security

  • Passwords are securely hashed and never stored in plaintext.
  • Authentication uses cryptographically signed tokens.
  • All communication between you and our servers occurs over HTTPS.

Your Rights

You may request:

  • Access to the data we hold about you.
  • Deletion of your account and all associated data.
  • Correction of any inaccurate data.

To exercise any of these rights, contact us at keanu@yomisensei.net.

Children's Privacy

Yomi Sensei is not directed at children under 13. We do not knowingly collect data from children under 13. If you believe a child has provided us with data, please contact us and we will delete it.

Changes to This Policy

We may update this privacy policy from time to time. Changes will be reflected by updating the "Last updated" date above.

Contact

If you have questions about this privacy policy, please contact us at keanu@yomisensei.net.