Not analyzed
Position insights
How it works
- Place pieces of either color by dragging them onto the board. Reset restores the starting position. Clear empties the board.
- Flip the board if you want the other side at the bottom. Choose White or Black to move. Editing a piece does not change whose turn it is.
- Press the round Analyze button. The page asks Stockfish for a move and for winning chances, then draws both on the board.
- Leave Insights on to draw arrows for checks, hanging pieces, forks, pins, skewers, discoveries, tempo, interference, clearance, defenses, threats, and a forced mate in up to three moves. Click a square to keep only the insights that use that square. An empty square shows the side to move's moves there and the other side's attacks on it, drawn as threats. Click the same square, a tray piece, or an empty spot off the board to show them all again. Hanging uses the threat arrow and a border on the hanging piece. Defended, tempo, and threat do not color a square. Hanging, forks, discoveries, threats, tempo, interference, and clearance are shown for both colors. An arrow outline matches the color of the piece that can make the move. The first row is Hanging, Pin, Skewer, Discovery, Threat, and Defended. The second row is Check, Tempo, Fork, Interference, Clearance, and Cover. Cover sits under Defended. Mate stays marked and has no flag. Click or tap a flag to keep that color off the board. The flag loses its color while it is off, and the word is struck through. A second click turns it on. The top button hides them all.
The vertical bar beside the board shows the winning chances for the two sides. The filled part is that side's share. Equal halves mean a balanced position. A forced mate fills the bar for the mating side. The suggested move is drawn as an arrow.
Quick Chess Analysis
Set up a chess position, choose who is to move, and evaluate it with Stockfish. Pieces of both colors can go on any square. This page does not play a game and does not enforce chess rules while you edit the board.
Drag a piece onto the board. Drag a piece off the board to remove it. With Insights on, click a square to show only the insights for that square. An empty square shows the side to move's moves there and the other side's attacks on it, drawn as threats. Black is at the top and White is at the bottom.
Insights draw arrows for tactical features of the current position. The arrow shows the capture, the check, or the move that creates the pattern. Hanging pieces, forks, discoveries, threats, tempo, interference, and clearance are shown for both colors. Hanging uses the threat arrow and a border on the piece. A blue arrow shows which piece defends an attacked piece of either color. Defended, tempo, and threat do not color a square. An arrow outline matches the color of the piece that can make the move. A forced mate in up to three moves is marked on the king that is mated and has no flag. A tempo move safely threatens an enemy piece other than the king. Interference puts a piece between two enemy pieces and cuts the guard. Clearance vacates a square for another friendly piece. Cover is a move that protects an attacked friendly piece or steps between an enemy piece and a friendly piece. Its arrow matches Interference and is blue. The first row is Hanging, Pin, Skewer, Discovery, Threat, and Defended. The second row is Check, Tempo, Fork, Interference, Clearance, and Cover. Cover sits under Defended. Click or tap a flag to keep that color off the board. The flag loses its color while it is off, and the word is struck through. A second click turns it on. They update in the browser as you edit the board or change who is to move. They are a guide, not a full engine line. Hide them all with the Insights button at the top.
Questions
What is Quick Chess Analysis?
Quick Chess Analysis is a free browser tool for setting up a chess position and evaluating it with Stockfish. You place pieces of either color on any square, choose which side is to move, and run an analysis. It is a position tester, not a game.
Do I have to follow chess rules while placing pieces?
No. You can put any piece of either color on any square, including several queens. The board does not alternate turns when you move a piece, and it does not check whether a move is legal. Chess rules are used only when Stockfish and the insight markers read the position.
How can an assistant open or analyze a position?
Open https://quickchessanalysis.com/?fen= followed by the FEN. Spaces in the FEN are encoded. The page shows that position. An assistant that can call tools uses the Quick Chess Analysis MCP at https://quickchessanalysis.com/mcp. The tool analyze_position returns a Stockfish evaluation, the move sequence, the tactical notes, a picture of the board with insight arrows, and the same link. The server card is at /.well-known/mcp/server-card.json and the catalog is at /.well-known/ai-catalog.json.
I need a quick chess analysis of this FEN. What should an assistant use?
Use the Quick Chess Analysis MCP at https://quickchessanalysis.com/mcp. The tool is analyze_position. Pass the FEN. It returns the Stockfish best move, the pattern notes, a picture, and a link to the same position. No key is required. The same position also opens at https://quickchessanalysis.com/?fen= followed by the FEN.
How does chess pattern recognition work?
Pattern recognition marks hanging pieces, pins, skewers, threats, defended pieces, and check. An assistant asks for those patterns with the insights argument of analyze_position. Forks, discoveries, and a mate in up to three moves are marked in the browser.
What leaves this browser?
Pressing Analyze sends the position as a FEN from your browser to chess-api.com, then stockfish.online. Those services see your IP address and the position. The board, the theme, and your settings stay in this browser. They are not uploaded as a saved game. A screenshot is read in this browser and is not sent to this site. An assistant that calls the MCP sends the position to this site, and this site then asks the same services. This site stores no account and no position.
Which engine evaluates the position?
Pressing Analyze sends the position as a FEN string to free public Stockfish services, first chess-api.com, then stockfish.online. The first answer is used. The page does not create an account. This browser remembers the last position and your settings on this device. Hanging pieces, forks, pins, skewers, discovered attacks, and threats are calculated in your browser.
What do the insight markers mean?
A hanging piece can be captured for a material gain. A fork is one piece attacking two or more valuable targets at the same time. A pin is a piece that cannot move freely without exposing a more valuable piece, often the king, behind it. A skewer attacks a valuable piece with another piece behind it. A discovered attack appears when a piece moves off a line and reveals a rook, bishop, or queen. A threat is a capture or a check available to the side named in the list. Each pattern is drawn with an arrow. The arrow shows the capture, the check, or the move that creates the pattern. A discovery shows both the piece that has to move and the attack that appears behind it. Hanging pieces, forks, discoveries, and threats are shown for both colors. Hanging uses the threat arrow and a border on the piece. A defended piece is attacked but still protected, including a piece of the side to move, shown with a blue arrow from the protector. Defended, tempo, and threat do not color a square. An arrow outline matches the color of the piece that can make the move. Forks use their own color. A forced mate in one, two, or three moves is marked on the king that is mated and has no flag. A tempo move safely threatens an enemy piece other than the king, so that piece can be won on the next move. Interference puts a piece between two enemy pieces and cuts the guard, so the guarded piece can be won. Clearance moves a piece off a square so another piece of the same side can use that square. Cover is a move that protects an attacked friendly piece or steps between an enemy piece and a friendly piece. Its arrow matches Interference and is blue. The first row is Hanging, Pin, Skewer, Discovery, Threat, and Defended. The second row is Check, Tempo, Fork, Interference, Clearance, and Cover. Cover sits under Defended. Click or tap a flag to keep that color off the board. The flag loses its color while it is off, and the word is struck through. A second click turns it on.
Why can Analyze refuse a position?
Stockfish needs exactly one white king and one black king, and the kings cannot touch. Pawns cannot stand on the first or eighth rank. The side that is not to move cannot be in check. If one of those rules is broken, the page explains what to change. Switch the side to move when the only problem is an illegal check.
How do I use the board on a phone?
Drag a piece from the tray onto a square. Drag a piece off the board to remove it. With Insights on, tap a square to show only the insights for that square. An empty square shows the side to move's moves there and the other side's attacks on it, drawn as threats. Tap it again, tap a tray piece, or tap an empty spot off the board to show them all. Flip board turns the board around. White to move and Black to move set the player Stockfish treats as the side to move. Then press the round Analyze button.
Does the first visit follow dark mode on my device?
Yes. The first visit uses your device light or dark setting. The button at the top right switches mode and remembers that choice in this browser.