Opening Tree

Opening Tree is a free chess opening explorer that turns your real game history into an interactive opening tree. Connect your Chess.com or Lichess account (or upload a custom PGN), and Opening Tree downloads your games, filters them by time control or date range, and builds a personalized opening tree visualized on a live chessboard with win, draw, and loss percentages for every branch.

The core idea is simple: instead of studying abstract theory, you study what is actually happening in your games. Every move in your tree shows how often you reached that position and how you fared from there. You can drill down into specific lines, compare your practical choices to grandmaster games, and quickly pinpoint which branches are costing you points.

Opening Tree is built for online players of all levels, from club players wanting to tighten their repertoire to coaches reviewing a student's opening tendencies. The tool is completely free, open source (GPL-3.0 on GitHub with 450+ stars), and available on web, iOS, and Android. No account or paywall required.