Tools

Small, focused utilities for chess engine developers. Each tool is a single page — no install, no login, shareable via URL.

FEN visualizer

Paste a FEN string and see the position rendered on a board. Flip the board, copy a shareable link, or load a known test position.

Available

Open tool

Bitboard inspector

Paste a 64-bit value to see which squares are set, or derive per-piece bitboards from a FEN. Click squares to toggle bits and copy the result back into your engine.

Available

Open tool

Perft tester

Count legal move sequences from any FEN. Compares against reference values for the standard CPW positions and gives a per-root-move divide breakdown for locating move-gen bugs.

Available

Open tool

PGN viewer

Paste a PGN and step through the game. Click any move to jump, grab the FEN at any ply, and share a link to a specific position.

Available

Open tool

perftcheck CLI

CLI

Cross-platform CLI that validates a UCI chess engine against ~28,000 known-correct positions and writes a JSON report. Self-contained binary for Linux, macOS, and Windows — no .NET runtime needed on the target.

Available

Open tool

More coming

UCI move tracer, attack maps, and other utilities are planned. Suggestions welcome on the project Discord.

Planned