Order Book Visualizer is a free online tool that simulates a limit order book in your browser — an animated depth chart, a live bid/ask ladder, and a synthetic order-flow engine firing limit, market, and cancel events — so you can learn how bids, asks, spreads, and depth work. All data is simulated; nothing on this page is a real market price.
Simulated data · for learning only
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Mid-price
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Spread
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Bid depth
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Ask depth
0
Events
Depth chart
Bids · cumulativeAsks · cumulativeMid-price
Order book ladder
Price
Size
Total
Simulation controls
Place your own limit order
Event feed
How to read an order book
Bid — the highest price buyers are willing to pay. Ask — the lowest price sellers will accept. The best bid and best ask sit on either side of the mid-price line.
Spread — best ask minus best bid. It is the cost of demanding immediacy; a tight spread means a liquid market, a wide one means thin trading.
Depth — resting size at each price. The depth chart stacks it cumulatively: the higher the curve at the middle, the more size is waiting near the touch.
Limit order — "I will buy/sell at this price or better." It rests in the book and adds depth. Market order — "fill me now." It takes depth, walking through price levels and pushing the mid-price.
Cancel — a resting order is withdrawn, thinning the book. Watch the feed: makers stepping inside a wide spread tighten it again.
Mid-price — the average of best bid and best ask. A reference point, not a tradable price.
Every number on this page is generated by a local random simulation for education. It is not market data, not a quote, and not financial advice.