About us & contact

Who we are

This site and the app Sudoku AI Coach are made and run by Chordup, an independent app developer brand that publishes several apps.

About this site

This site teaches you how to solve sudoku step by step with the techniques people use. The rules, a learning path, a guide to each technique, a solver that explains the next move, and puzzles you can play in your browser are all free.

How the puzzles and explanations are made

Puzzles and explanations are made and checked by the same solver as the app, a program that solves only with human techniques. Every puzzle has exactly one solution and can be solved without guessing. The steps in each example are moves the solver actually found.

Text in languages other than Japanese and English was translated with AI and has not yet been reviewed by native speakers. If you notice anything odd, please let us know by email.

Advertising

The site and the browser version may show ads from Google. See the privacy policy for how ads and cookies are handled.

Contact

For feedback, bug reports or press inquiries, email us at info@chordup.io.

In the app, you can also use the Me tab → Settings → "Send feedback".