Mahjong Metrix

Privacy & Cookie Policy

Last updated: September 19, 2026

1. Introduction

Welcome to Mahjong Metrix (“we”, “our”, or “us”). We respect your privacy and are committed to protecting the personal data of our players, tournament organizers, and club members. This Privacy & Cookie Policy explains what data we collect, how we use it, your rights, and how you can manage or delete your information.

2. Google OAuth & Information We Collect

Mahjong Metrix provides social sign-in via Google OAuth to make account creation fast and secure. When you choose to authenticate with Google, we request access only to your public profile and email address.

Data collected via Google OAuth:

  • Name & Display Name: Used to display your player handle in tournaments, tables, and leaderboards.
  • Email Address: Used as your unique account identifier and for critical account-related notices.
  • Profile Image / Avatar: Displayed on your player profile and match seating tables.

We never request access to your Google Drive, Gmail messages, contacts, calendar, or any other private Google data.

3. How We Use Your Data

We use your information exclusively to operate the Mahjong Metrix platform:

  • Authenticate your account and maintain active sessions.
  • Maintain your competitive player profile and assign tables in Riichi Mahjong tournaments.
  • Calculate, record, and publish match scores, Uma placement bonuses, and seasonal ratings (Yonma and Sanma, offline and online).
  • Display public rankings and club leaderboards.

We do not sell, rent, or trade your personal data to advertisers, data brokers, or any third parties.

4. Cookie & Storage Policy

We believe in privacy by default. We use only strictly necessary cookies and browser storage essential for site functionality:

  • Authentication Tokens (HTTP-only cookies): We use secure, encrypted session cookies provided by NextAuth.js to verify your identity when you are logged in.
  • Theme Preferences (Local Storage): We store your selected theme (Dark mode or Light mode) in your browser's local storage.

We do not use third-party advertising cookies, behavioral tracking scripts, or cross-site fingerprinting.

5. Data Retention & Permanent Account Deletion

You have full control over your personal data. You may permanently delete your Mahjong Metrix account and all associated personal data at any time:

  1. Log into your account and navigate to Account Settings.
  2. Scroll down to the “Delete Account” section.
  3. Type the confirmation phrase and confirm deletion.

When you delete your account, your user record, email address, OAuth connections, active sessions, and private profile data are immediately and permanently removed from our databases.

6. Contact Us

If you have any questions or concerns regarding this Privacy & Cookie Policy, or wish to submit a data inquiry, please contact us at:

support@mahjong-metrix.com