Polygate

Polygate is a toolkit for building, analyzing, and managing chess opening books in the Polyglot format (.bin) — completely offline and without installation.

WHAT POLYGATE CAN DO

Polygate produces ready-to-use .bin books for your engine or chess GUI from a range of sources:

• PGN game collections (e.g. engine games or master games)
• ECO opening codes (A00–E99)
• the Lichess Cloud Eval database (~395 million evaluated positions)
• existing EPD files

FEATURES

• Wizard for a quick start
• Win-oriented books: optionally include only the moves of the winning side (e.g. only games that end in mate) — no losing moves in the book
• Per-move evaluations from the Lichess eval database, with engine analysis as a fallback — works with Stockfish or any other UCI engine
• Interactive book browser: play through the book on a real chessboard, drag pieces or click any move in the table, browse the whole book as a tree, and compare two books side by side
• Statistics: evaluation and depth distribution, game-phase breakdown, and overlap between books
• Tools: merge, filter, deduplicate, verify, repair — and subtract one book from another (move-exact for .bin, position-exact for .epd/.fen)
• Book upgrade: deepen existing books iteratively
• Recipes: save settings and reuse them anytime
• Built for large data: memory-friendly streaming (including the 89+ GB database), reads compressed .zst files directly, crash recovery preserves your progress
• Bilingual (German/English), drag & drop, automatic DPI scaling with an adjustable board and interface zoom

Polygate was created during the development of the chess game Chesslantis. Feel free to drop by: https://ayk0-bo.itch.io/chesslantis

SYSTEM REQUIREMENTS

• Windows 10/11 (64-bit)
• Optional for full functionality:
  • Stockfish or a comparable UCI engine for engine analysis
  • The Lichess eval database (free download at database.lichess.org). Both are simply linked from the settings.
• Works memory-efficiently; storage needs depend on your data