Legal

Privacy & Terms

Last updated: May 2026

We collect the minimum needed to make the app work. No ads, no selling your data, no third-party tracking beyond what Supabase and the Claude API require to function.

Privacy Policy

What we collect

汉字练习 uses Supabase for authentication and data storage. The following tables describe exactly what is stored on your behalf when you create an account and use the app:

auth.usersmanaged by Supabase Auth

Email address, hashed password (we never see the plain text), account created timestamp.

settings

Your starting HSK level (1–6), grading strictness preference, sentences per round, rounds before a vocabulary unlock, words unlocked per round, pinyin display mode (always / tap / never), hints display mode (before / after / never), and timestamps.

vocab_list

Each vocabulary word you have unlocked: the Chinese character(s), pinyin, English meaning, part of speech, topic tag, HSK level, when it was unlocked, how many times you have seen and answered it correctly, the last time you saw it, the last time you answered it correctly, and its current mastery level (learning / reviewing / mastered).

progress

Your cumulative totals: rounds completed, sentences completed, sentences in the current round, current round number, rolling accuracy percentage, current streak in days, longest streak ever, the last time you practiced, and which unlock you last claimed.

daily_stats

One row per calendar day: sentences attempted, sentences answered correctly, rounds completed, and words seen that day. Used to display your activity history.

round_summaries

One row per completed round: round number, total sentences, correct sentences, accuracy percentage, longest in-round streak, and the strictness level used.

sentence_attempts

One row per graded sentence: the Chinese sentence, its pinyin, your typed answer, the correct answer, your score (0–100), whether it was marked correct, the strictness used, the vocabulary words that appeared in the sentence, and the timestamp.

We do not collect your name, phone number, location, payment information, or any information beyond what is listed above. We do not use advertising cookies or third-party analytics trackers.

How we use it

Your data is used exclusively to:

  • Authenticate you and keep your session secure
  • Generate AI sentences using only your known vocabulary
  • Track your accuracy per word and surface struggling words more often
  • Restore your progress when you return to the app
  • Remember your theme and display preferences

Your practice data is never used to train AI models. Sentences submitted to the Claude API for grading are not retained by us beyond the immediate API call.

Third-party services

汉字练习 uses the following third-party services:

  • Supabase — authentication and database hosting. Your account data lives in a Supabase project. Supabase Privacy Policy →
  • Anthropic (Claude API)— AI sentence generation and answer grading. Each sentence and your typed translation are sent to the Claude API to produce a score and feedback. Anthropic's data handling applies. Anthropic Privacy Policy →

There are no advertising networks, analytics trackers, or data brokers involved.

Data retention

Your data persists in Supabase for as long as your account exists. Deleting your account removes all associated practice data, settings, and authentication records.

To request account deletion, email us at the address in the Contact section below. We will process deletion within 7 days.

Your rights

You have the right to:

  • Access a copy of the data stored about you
  • Correct inaccurate data
  • Delete your account and all associated data
  • Withdraw consent at any time by deleting your account

To exercise any of these rights, contact us at the email address below.

Terms of Use

Acceptable use

汉字练习 is a personal study tool. By using it, you agree not to:

  • Scrape, reverse-engineer, or redistribute the app or its API
  • Share account credentials with others
  • Use the app in any way intended to harm, spam, or abuse Supabase or Anthropic infrastructure

The app is provided free of charge for personal educational use. Commercial use is not permitted without written consent.

No warranties

汉字练习 is a student project, provided as-is without warranty of any kind. We make no guarantees about uptime, accuracy of grading, or suitability for any particular purpose — including passing your Chinese class (though we hope it helps).

We reserve the right to modify, suspend, or discontinue the service at any time without notice.

Contact

Questions about your data, deletion requests, or anything else:

Email: karlmchazlettjr@gmail.com

This policy was last updated May 2026. We'll post any changes here with a new date.