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Instantly resets all 32 pieces to their standard starting squares. Any computer play, clock, or analysis session is stopped first. Your move history is cleared and the position auto-saves as a new game record.
Enables free play from the current position — you move for both colours. Useful for exploring openings, teaching yourself tactics, or setting up a position and continuing from there. Works with Undo/Redo so you can explore branches.
Opens the Computer Settings panel where you choose which colour each side plays (player or computer) and how many seconds the engine waits before moving (0 = instant, blank = manual trigger). The engine runs silently in the background so the page stays fully responsive while it thinks — you can still scroll, click, and interact normally. A "thinking…" badge appears on screen while the engine is calculating its move.
Challenge any visitor to either a Quick game (up to 10 minutes per move — you set the time limit, default 2 min) or a Slow correspondence game with no time pressure. Features: ELO rating system starting at 1200 (K=32 for first 30 games, then K=16), leaderboard of top 10 players, clock-stop / pause option, 30-second flashing countdown warning, automatic forfeit on timeout, resign button, and a waiting lobby where open challenges are listed.
Saves the current board as a FEN string to browser local storage. The FEN & PGN section opens automatically so you can copy the string. Up to 100 positions are stored and the last 12 are always shown for quick reload. Positions are also auto-saved after every move.
Runs Stockfish on the current position continuously, displaying the top candidate moves with centipawn scores and principal variations. Toggle "Max Depth (1 Line)" for a single deep line instead of 3 lines. Analysis updates live as you make moves.
Choose from 8 board colour themes (Classic, Green, Blue Steel, Night, Walnut, Mono, Coral, Jade) and 8 piece colour styles (Classic, Black & White, Ocean, Copper, Forest, Violet, Crimson, Gold). Or pick any custom colour with the colour pickers. A live preview shows the chosen combination. Settings are remembered between sessions.
Click any piece in the palette then click any board square to place it. Remove a piece by clicking an occupied square in the palette (eraser) or clicking the piece directly. Set the side to move and configure castling rights. Note: the position must have both a white king and a black king on the board before you can click "Done — Play This" — without both kings the position is illegal and play cannot begin.
Paste any PGN game text and click Load. Navigation buttons let you step forward, backward, to the first move, or to the last move. The full move list is shown with each move clickable. Useful for studying master games or reviewing your own games.
The engine generates a random board position and verifies there is a forced mate in exactly two moves. Choose Easy (fewer pieces), Medium, Hard (more pieces, trickier), or Custom — with filters for: unique solution only, no check on first move, sacrifice required, remove non-essential pieces, mate may not involve the Queen, mate may not involve the Rook. A new puzzle is generated every time.
Adds a chess clock to your game. Choose Elapsed Time (stopwatch — counts up for each player) or Countdown (each player has a fixed time budget). Preset time controls: 1, 3, 5, 10, 15, 30 minutes, or enter any custom duration. The active player's clock runs automatically and switches on each move. Pause and reset buttons included.
Rotates the board 180° so you view it from the other side. Rank and file labels update accordingly. Useful when playing both sides or when showing the board to a second player sitting across from you.
Undo takes back the last move; Redo replays it. You can step back as many moves as you like and explore a different line — the redo stack is preserved until you make a new move. Works in both Play Both Sides and Play Computer modes.
Every move is recorded in standard algebraic notation (e.g. 1. e4 e5 2. Nf3…) and displayed in the Move History section, which scrolls automatically to the latest move. Captures, checks, and checkmate are annotated with the standard symbols (×, +, #).
The FEN & PGN section is always visible below the board. Any number of games can be saved — they are stored automatically and retrieved with a single click. For convenience the last 10 saved games are always shown, each with its final position in FEN format so you can see at a glance where each game ended. Clicking any saved game instantly reloads it onto the board, replacing the current game. This makes it easy to jump backwards and forwards between different saved games. A paste box is also available for loading any FEN string or PGN game from an external source. Hovering a saved FEN shows a miniature board preview.
Hover over any saved FEN entry or move in the history panel and a small floating chessboard appears showing that position, complete with a move arrow. Makes it easy to scan saved positions without loading them.
Load a plain-text file of FEN strings (one per line) and the engine tests each one for a forced mate in two, logging pass/fail results as it runs. Found solutions are collected in a Results panel and can be loaded onto the board individually. Useful for building and verifying puzzle databases.
A real-time chat room on the Chess Chat page, backed by Google Sheets. Messages are shared with every visitor. Topics: General, Openings, Puzzles, Endgames, Strategy. Messages refresh automatically every 15 seconds, or tap "↻ Refresh" for instant update. Enter your name, optional location and age, and post. No account required.
Registered players in the vs Human mode earn an ELO rating. Starting ELO is 1200 (or your own estimate if you enter one). K-factor is 32 for the first 30 games and 16 thereafter. Win/loss/draw records are tracked. The top 10 players by ELO are shown on the in-lobby leaderboard. Your token (stored in the browser) keeps your identity without a password.