Chess analysis should explain the game, not only score the moves.

zen.reinit.net is a personal chess game library and analysis workspace. It connects browser-based Stockfish analysis, explanations from Cassia, alternative-line exploration, and continuation simulation in one review flow.

The problem

A bad-move label is the beginning of a useful review.

Chess engines are excellent at finding stronger moves, but an evaluation change does not automatically tell a player what they misunderstood. Cassia turns engine-grounded facts into a plain-language explanation of the threat, tactical detail, positional concession, or plan behind the move.

The workflow

Keep the game, find the moment, understand it, and try again.

Personal game library

Import games from Chess.com, Lichess, or PGN and keep reviewed games together in Dashboard.

Stockfish analysis

Analyze positions in the browser, classify moves, and move directly to the important turning points.

Cassia explanations

Ask why a move failed and connect the engine line to a concrete chess reason.

Explore and Simulation

Play another move yourself or let the engine continue the alternative position at a chosen strength.

Local by default

Start without an account. Analyze with the engine in your browser.

The core game library can be used locally, and Stockfish runs as WebAssembly in the browser. Account and optional AI-assisted features have separate data behavior described in the Privacy Policy and AI Disclosure.