Contextus is a macOS app that helps you learn English from the articles you actually read: detect the words that are hard for your level, save them with the sentence they came from, and practice until you can use them — with AI feedback in your own language.

If you need help, email us and we'll get back to you.

Contact: champion790713@gmail.com

Last updated: July 12, 2026

Contextus ("the App," "we," "us") is a macOS reading and vocabulary app developed by Pin-Yuan Chen. This Privacy Policy explains what information the App handles, how it is used, and the third parties involved. We designed Contextus to collect as little as possible: there is no account, no login, and we never ask for your name, email, or any sign-in.

Summary

• Your articles, saved words, and study progress are stored locally on your Mac. We do not have a copy and cannot see them.
• When you use an AI feature (detecting difficult words, grading a sentence, or checking a recalled definition), the specific text for that request is sent over an encrypted connection to our processing server and on to our AI provider (Anthropic) solely to generate the response, then returned to you.
• Subscriptions are handled by Apple and RevenueCat. We receive your subscription status and an anonymous user identifier — never your payment details.
• We do not show ads, do not track you across other apps or websites, and do not sell your data.

Information we handle

1. Content you submit for AI features

When you ask the App to detect difficult words in a passage, grade a sentence you wrote, or evaluate a definition you recalled, the App sends the text of that request to our server (a Cloudflare Worker), which forwards it to Anthropic to generate the AI response. This may include the passage or sentence text you provide. It is used only to produce your result and is not used to build a profile of you.

2. Subscription and purchase information

Contextus is a paid subscription app. Purchases are processed by Apple and managed through RevenueCat. From these services we receive your subscription status (for example, whether your trial or subscription is active) and a pseudonymous user identifier generated by RevenueCat. We use this identifier to unlock the app and to count your monthly AI grading usage against your plan's fair-use limit. We never receive or store your credit card number or other payment details — those stay with Apple.

3. Usage identifier

The App uses the pseudonymous RevenueCat user identifier described above to enforce per-account monthly usage limits on our server. This identifier is not linked to your name, email, or any real-world identity, because we never collect those.

4. Data that stays on your device

Your articles, saved words, review history, chosen native language, and study progress are stored locally on your Mac using Apple's on-device storage. The App also records basic, anonymous usage events (such as "app opened" or "word saved") to a local file on your Mac to help improve the experience. This local information is never transmitted to us or to anyone else and is removed when you delete the App.