Privacy Policy

Third Door LLC ("we") has established this Privacy Policy for "HSK 3.0 Practice Tests" (the "Site"). It explains how we handle information about users of the Site.

1. Information we handle

The Site does not require registration or an account, and never asks for your name, address, phone number or email address.

• Stored in your browser: settings, stars earned, mock test results and a device ID (a random identifier). These stay in your browser; only the device ID is ever sent to us.
• Sent for AI feedback: only when you use "Check with AI", we send your answer, the question number and the device ID to our grading server.
• Network information: loading the Site, pictures, audio and fonts sends network information such as your IP address and browser type to the respective providers.

2. AI feedback on writing

When you use "Check with AI", your answer and the question information (the given word, the topic, sample answers and the picture) are sent through our grading server (run on Cloudflare, Inc.) to Claude, an AI provided by Anthropic, PBC, which returns feedback. Please do not include your name or other personal information in your answers.

• To prevent overuse, the grading server records the number of uses per day for each device ID and IP address. These records are deleted after the day ends.
• The grading server's logs contain only the question number and processing volume, not the text of your answer.
• Information sent to Anthropic is handled under Anthropic's privacy policy and API terms.
• AI feedback is for reference only and does not guarantee accuracy or reflect actual HSK scoring.

3. Purposes

• To show feedback on your writing
• To prevent overuse or misuse of AI feedback
• To find and fix problems and improve the Site

4. External services

• Anthropic (Anthropic, PBC) — AI feedback on writing
• Cloudflare (Cloudflare, Inc.) — running the grading server
• Amazon Web Services (Amazon Web Services, Inc.) — delivering pictures and audio
• Google Fonts (Google LLC) — delivering fonts

The Site shows no ads and uses no analytics tools.

5. Disclosure to third parties

We do not provide user information to third parties except as required by law or for other legitimate reasons. Sending information to the services listed in sections 2 and 4 is done within the scope of this Policy.

6. Deleting information in your browser

You can delete the information stored in your browser by clearing this site's data (site data / local storage) in your browser.

7. Children

Children should use the Site with a parent's or guardian's consent. We do not knowingly collect personal information from children under 13.

8. Changes

We may update this Policy as needed. Changes take effect when posted on this page.

9. Contact

Third Door LLC
ku-obe@outlook.jp

Effective: November 15, 2026