Sudoku Buddy

The joy is in figuring it out.

Keep your pencil. Keep your puzzle. Get a little help when you need it.

Sudoku Buddy is an Android companion for standard 9×9 Sudoku on paper. Scan a puzzle—including the answers you have already written—check the reading, and ask for a hint that explains the next move. It is made to help with the puzzle already on your page, not replace it.

Website · Usage guide · Support · Privacy

See the app

These are real Android screens; the current release may differ slightly. See more on the website.

Get the app

Google Play — Android: Get Sudoku Buddy. As of 29 October 2026, version 1.0.4 (code 243) is active in both Production and Internal testing. It needs Android 8.0+ and a camera. Invited testers can use the internal-test opt-in. Version 1.0.5 (code 244) is attached to an unsubmitted Internal testing draft and is not available to testers. No public APK is published in this repository.

What it helps you do

• Read printed clues and handwritten progress, then correct a misread square.
• Check your answers and reveal a hint in stages, with the relevant cells and solving technique highlighted.
• Reopen saved puzzles from on-device history and continue after a break.

Scanning, checking and hints work on the phone, including offline. Handwriting, erasures and lighting can cause misreads, so review the recognized grid before relying on a check or hint.

Support, feedback and bugs

Get support · Share feedback · Report a bug

GitHub issues and attachments are public. Remove personal details from reports and use the private contact option in the support guide for a photograph or example you do not want to post publicly.

Privacy and release status

Privacy policy · Local-data deletion

Camera recognition and puzzle history stay on the device. Users can submit an uncertain-reading report to Freevia for private recognition analysis and training; reports include the puzzle photo, recognition results and corrections. Automatic sharing is optional and off by default. The app has no account, ads, routine usage analytics or ad tracking. See the privacy policy for report handling and deletion details.

Sudoku Buddy's original source code and documentation are licensed under Apache License 2.0. Freevia and Sudoku Buddy names and logos remain subject to their respective trademark rights; the license does not grant branding or endorsement rights. Third-party components retain their own licenses; see the notices and bundled license texts.

For contributors

The SwiftUI iOS port shares Kotlin recognition, solver and teaching logic, with native scanning, durable history, localization and consent-based feedback. Open iosApp/SudokuBuddy.xcodeproj; see iOS development for setup and tests, and App Store preparation for the submission packet and remaining account/device gates. The iOS preview supports camera/photo scanning, manual entry, checking, hints, and on-device history with automatic puzzle and progress restoration after restart. It also includes the 71 Android language catalogs, launcher artwork, offline notices, and Android overlay colors in a dark SwiftUI interface. Review scanned cells before play; the iOS capture path still needs validation on a physical iPhone.

The Android app uses Kotlin, Jetpack Compose, CameraX and OpenCV, with separate modules for recognition and deterministic solving. Use JDK 21 and Android SDK platform 36. From the repository root:

.\gradlew.bat build

On macOS/Linux, use ./gradlew build. The usage guide and Play preparation notes provide more detail. A passing local build is not a Play release.