PolyMind Chess
Play
Choose a suitable strength, resume a saved game and ask for a hint whenever you need one.
One board. Many minds.
Understand your moves, beyond the score.
PolyMind Chess combines a real chess engine, several decision engines and a coach who can talk through your game. You play; Léon explains what really happened.
The product
A personal coach built around your games.
Play in your browser against Stockfish or an opponent powered by JEV, Decider, Qwen3, MiniCPM5 or Qwen3.5. Léon explains key moments, answers written or spoken questions, prepares a review and remembers recurring mistakes stored on your device.
Understand
Arrows, evaluations and explanations connect Léon’s words to the actual position.
Review
The review identifies good moves, inaccuracies, mistakes and blunders using Stockfish analysis.
Improve
Key moments become exercises, while your profile tracks recurring themes in your games.
Verifiable architecture
Each mind has a clear role.
- chess.js
- Applies the rules, generates legal moves and detects the end of the game.
- Stockfish 19
- Runs locally in WebAssembly to calculate evaluations, best moves and opponent strength.
- JEV
- Chooses between legal options described by the code and handles certain bounded requests. JEV does not define the rules or establish chess truth.
- Decider
- An open reproduction of the “System One” family: it reads typed questions and returns a probability for each option. It runs in the browser after a 1.3 GB download.
- Qwen3, MiniCPM5, Qwen3.5
- Open language models run locally, as in LocalClaw Labs: their probabilities for each option are read without generating text. Downloads range from 0.4 GB (Qwen3 0.6B) to 3 GB (Qwen3.5 4B, requiring WebGPU).
- Léon
- Turns calculated facts into clear advice, tracks your difficulties and answers in the context of the game.
- Your browser
- Stores games, your profile and preferences. Voice and transcription models are downloaded and run locally where the browser supports them.
Decision Model Lab
Chess as a decision lab.
PolyMind Chess goes beyond a single engine score. A shared selector lets different systems play from the same legal candidates, so you can observe where their choices agree and differ.
Current status: JEV uses the TypeSafe API; Decider, Qwen3, MiniCPM5 and Qwen3.5 run entirely in the browser. A local model downloads only when you select it and start a game, with its size shown beforehand.
Frequently asked questions
What you need to know.
What is PolyMind Chess?
A conversational chess coach for playing, reviewing games and learning from mistakes.
What do Stockfish and JEV do?
Stockfish calculates the position. JEV provides bounded judgments between choices prepared and checked by the software.
Can I use another engine instead of JEV?
Yes. Decider, Qwen3, MiniCPM5 and Qwen3.5 answer the same questions as JEV, directly on your device.
Does the product run locally?
Stockfish, game data and the main voice features run in the browser. JEV features use the TypeSafe API through a server relay.
Is this an official TypeSafe product?
No. PolyMind Chess is an independent product that can use TypeSafe’s JEV service when configured.