thomasahle/sunfish

Health v2 · maintenance only

Flags: no_license

Adoption not part of the score

3271 stars · 583 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

Sunfish is a simple but strong chess engine written in Python in roughly 111 lines of code, using MTD-bi search with piece-square table evaluation, plus a small NNUE variant. It speaks the UCI protocol so it can be played in a terminal, via GUIs like Arena or Cute Chess, or on Lichess.

Use cases

• play chess against an engine in the terminal
• hook a chess engine into a UCI GUI or tournament tool
• learn how a chess engine works by reading minimal code
• experiment with search algorithms and evaluation functions
• build a deep learning chess program on a simple base
• run engine matches with fastchess or cutechess-cli

When to choose

• you want a tiny, readable chess engine to study or modify
• you need a lightweight UCI engine for casual play or testing
• you want a platform for experimenting with chess AI research

When to avoid

• you need maximum playing strength comparable to Stockfish
• you need a production engine with extensive opening books and tablebase support
• you need a non-GPL-licensed engine

Facets

application · maturity active

game-engine cli machine-learning artificial-intelligence gaming-tools python cli cross-platform chess chess-engine uci nnue minimalist didactic game-development

Member repositories

For agents

markdown · JSON · MCP: product_card(name="thomasahle/sunfish")