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Privacy Policy

Last updated: April 30, 2026

Overview

NihongoTube is a browser extension that helps Japanese learners filter YouTube content by language and difficulty. This policy explains what data we collect, why we collect it, and how we handle it. We do not have user accounts, we do not sell data, and we do not use third-party advertising or analytics services.

Data we collect

1. JLPT analysis submissions

When the extension analyses a YouTube video, it calculates a JLPT difficulty estimate from the video's captions. By default, this analysis (along with the video's public metadata: title, channel, category, view count, duration, keywords) is submitted to our API to improve difficulty estimates across all users.

Each submission includes:

  • A randomly generated install identifier (UUID) unique to your browser profile, not linked to your identity
  • Your browser type and extension version
  • Linguistic metrics derived from the video's captions (word counts, JLPT level distribution, words per minute, etc.)
  • Public video metadata fetched from YouTube

You can opt out of these submissions at any time in the extension settings. Opting out does not affect any other functionality.

2. User JLPT corrections

If you manually correct a JLPT estimate using the rating dialog, we record your correction alongside the extension's original prediction. This uses the same install identifier described above.

3. Uninstall feedback

When you uninstall the extension, you are directed to an optional feedback page. Submitting feedback requires a reason (selected from a list); an email address and free-text comment are optional. If you provide an email, it is used solely to follow up on your feedback and is not stored in a database or used for marketing.

Data stored locally in your browser

The following data is stored only on your device using browser extension storage and is never transmitted to our servers:

  • Your extension settings and preferences
  • Your watch time history (video ID, title, channel, timestamps, duration)
  • Your channel whitelist
  • The install identifier UUID

You can clear this data by uninstalling the extension or clearing your browser's extension storage.

IP addresses

When your browser sends a request to our API, the server receives your IP address. We immediately hash it using salted SHA-256 and store only the hash. The hash is used for rate limiting. We do not store IP addresses in plaintext.

Although practically irreversible, hashed IP addresses may still be considered pseudonymous data under GDPR. We disclose this in the interest of transparency.

YouTube data

The extension reads video metadata and captions directly from YouTube to perform its filtering and analysis. This data is processed locally in your browser. Caption content is not stored on our servers.

Third-party services

  • Resend: used to deliver uninstall feedback emails to our inbox. Your email address (if provided) passes through Resend's servers.
  • Cloudflare: used for DNS, CDN, and rate limiting. Cloudflare may process request metadata including IP addresses in accordance with their own privacy policy.

We do not use Google Analytics, Mixpanel, Sentry, or any other analytics or error-tracking service.

Data retention

JLPT analysis submissions and user corrections are retained to improve difficulty estimates. Hashed IP addresses are retained as part of submission records. There is currently no automated deletion schedule.

Your rights (GDPR)

If you are in the European Economic Area or UK, you have rights including access, rectification, erasure, and objection. However, because all submissions are pseudonymous and not linked to your identity, we have no means of identifying which records belong to you. As a result, we are unable to fulfil individual erasure or access requests for submitted data.

Data stored locally in your browser (watch history, settings, preferences) is entirely under your control and can be deleted at any time by uninstalling the extension or clearing your browser's extension storage.

For any other privacy questions, contact hello@nihongotube.app.

Children

NihongoTube is not directed at children under 13. We do not knowingly collect data from children.

Changes to this policy

We will update this page if our data practices change. The date at the top reflects the most recent revision.

Contact

Questions about this policy: hello@nihongotube.app