Nibbler

Nibbler is a free, open-source chess analysis GUI built specifically to work with Leela Chess Zero (Lc0), the neural network-based chess engine. It runs Leela in the background and continuously displays the engine's opinions about the current position, giving players a live, interactive analysis experience that differs from traditional move-by-move review.

The interface visualizes Leela's top choices graphically and includes a winrate graph, making it easier to understand the engine's evaluation at a glance. For players who want to go deeper, Nibbler can optionally display Leela's internal statistics including N, P, Q, S, U, V, and WDL values for each candidate move. These metrics give insight into how Leela is thinking, which is useful for players trying to understand neural network chess evaluation.

Beyond analysis, Nibbler supports full-game automatic analysis, the ability to play against Leela from any position, and Leela self-play from any position for opening or endgame research. While it was designed with Lc0 in mind, Nibbler also supports traditional UCI engines like Stockfish, making it a capable general-purpose GUI.

Nibbler is written in JavaScript and distributed as a desktop application for Windows and Linux. The source code is fully open on GitHub under the rooklift/nibbler repository, and it has an active community of users in the Leela Chess Zero ecosystem.