Last updated: February 23, 2026

This Privacy Policy applies to the Metheus website (`metheus.app`) and the Metheus browser extension (collectively, the "Service"). It describes what information we collect, how we use it, and the choices you have.

1. Information We Collect

We collect information you provide directly, such as your email address, account credentials (or sign-in provider details), support requests, and subscription details. If you use learning features, we also process the content and metadata you choose to import (for example, decks, books, subtitles, notes, vocabulary progress, and study statistics).

We may also collect technical and usage information needed to operate the Service, such as device/browser type, basic diagnostic logs, timestamps, and feature usage events. If you use the browser extension, processing can occur on pages you visit in order to extract subtitles/text, provide dictionary features, and sync your study data when you enable those features.

2. How We Use Information

We use information to provide and maintain the Service, authenticate your account, synchronize your learning data across devices, process subscription/billing workflows, personalize your learning experience, improve reliability and performance, prevent abuse, and respond to support requests.

3. Browser Extension Permissions

The Metheus extension may request permissions such as access to tabs, page content, local storage, context menus, side panel, and capture-related features. These permissions are used to provide extension functionality (for example: subtitle mining, dictionary popups, media capture/import workflows, and syncing data with your Metheus account). We do not use these permissions to sell personal data.

4. Storage and Service Providers

We use third-party infrastructure providers to operate the Service, including providers for authentication/database services, file/object storage, hosting/CDN, and payment processing. Examples may include Firebase (authentication and app data), Backblaze B2 (storage), Vercel (hosting/deployment), and Lemon Squeezy (payments). These providers process data on our behalf according to their own terms and privacy policies.

5. Data Sharing

We do not sell your personal information. We may share data only as needed to operate the Service, comply with law, enforce our terms, protect users and the platform, or as part of a merger, acquisition, or asset transfer. When possible, we limit shared data to the minimum necessary.

6. Cookies and Local Storage

Metheus uses cookies and browser storage for essential functions such as session management, authentication, preferences, and performance. The extension also uses browser storage to store settings and local study state. Disabling cookies/storage may cause some features to stop working correctly.

7. Data Retention

We retain account and learning data for as long as your account remains active or as needed to provide the Service. If you request deletion, we will make commercially reasonable efforts to delete or anonymize your data, subject to legal obligations, fraud-prevention needs, and backup/archival cycles.

8. Security

We use reasonable administrative, technical, and organizational measures to protect your information. Data is transmitted over HTTPS/TLS where supported. However, no method of transmission or storage is completely secure, and we cannot guarantee absolute security.

9. Your Rights and Choices

Depending on your location, you may have rights to access, correct, export, or delete your personal information, and to object to or restrict certain processing. You may also cancel subscriptions through the applicable billing provider. To request data deletion or access, contact us using the email below.

10. Children's Privacy

The Service is not directed to children under 13 (or the minimum age required in your jurisdiction). We do not knowingly collect personal information from children in violation of applicable law. If you believe a child provided us data, contact us and we will investigate.

11. International Users

If you use the Service from outside the country where our infrastructure or providers are located, your information may be transferred to and processed in other countries. By using the Service, you understand that these transfers may occur.

12. Changes to This Policy

We may update this Privacy Policy from time to time. If we make material changes, we may provide notice through the Service or by other reasonable means. The updated version will be posted on this page with a revised "Last updated" date.

13. Contact and Data Requests

For privacy questions, account deletion requests, or data access/export requests, contact us at metheus.app@gmail.com.