Order book heatmap: reading resting liquidity in crypto

An order book shows the limit orders waiting at each price right now. One second later it has changed, and the previous picture is gone. An order book heatmap keeps those pictures: time runs from left to right, price from bottom to top, and every cell is coloured by how much size was waiting at that price at that time. Large orders that stay put become bright horizontal bands; orders that come and go leave only faint marks.

The Help Center describes the live Level 2 order book among the order-flow tools. This guide covers the heatmap that records the book over time on AlertaChart, how to read it, and what it cannot tell you.

What resting liquidity is

A limit order that does not trade immediately rests in the book until someone trades against it or its owner cancels it. Those resting orders are the market's liquidity: the size a market order can fill against. Exchanges publish changes to the book as a depth stream; on Binance each update gives the full quantity now waiting at a price, and a quantity of zero removes that price from the book.

AlertaChart turns that stream into a picture. Each cell shows the average size that rested at that price during that slice of time, weighted by how long it stayed. An order shown for a moment barely tints its cell; one that sits for minutes paints a band.

How to read the heatmap

• Bright bands are large orders that stayed. Above the price they are offers waiting to sell, below it bids waiting to buy.
• A band that ends when the price reaches it was traded through: market orders filled it. The trade dots at that spot show the volume.
• A band that ends before the price gets there was pulled: the orders were cancelled or moved.
• Trade dots mark aggressive trades. They grow with volume and are split between the buy and sell colours by each side's share.
• Colours are relative. The brightest colour belongs to the largest resting sizes in the current view, so zooming or scrolling can recolour the same order. Compare bands within one view, not between screenshots.

Hover a cell to read it exactly. Resting is the average size in that cell, Book now is what waits at that price at this moment, and Not recorded here means the book was not known for that stretch.

Walls that vanish, and spoofing

A big order can be placed to influence others and cancelled before anyone trades against it. US commodity law calls this spoofing, describing it as bidding or offering with the intent to cancel before execution, and prohibits it on markets subject to the rules of a CFTC-registered entity, such as a registered futures exchange. Whether a rule like that covers a given crypto exchange depends on where and how that exchange is regulated. Either way, a heatmap cannot see intent: it only shows that size appeared and later disappeared. Orders are also cancelled for ordinary reasons, such as a changed plan or a price that moved away. Treat a wall as a fact about the book at that moment, not as a promise that the price will stop there.

With candles or Bookmap view

When the heatmap is on, the toolbox offers two views under View:

• With candles: the heat sits under the normal candles.
• Bookmap: where the book was recorded, an opaque dark background replaces the candles, a line follows the traded price and thin taker-volume bars run along the bottom. The chart's own volume is hidden in this view. Stretches without a recording keep their candles.

Both views can show the current order book as a ladder near the right edge: offers above, bids below, a bar and a size for each price step. While that ladder is on and the newest trade is on screen, the chart follows the live price: before the live point reaches the ladder, the chart scrolls by itself. In the Bookmap view the chart moves in occasional jumps that put the live point back by part of the free space; with candles it moves one bar at a time. Scroll back into history and the chart stays where you put it.

Perpetual and spot books

AlertaChart records the books of Binance's top 50 coins by 24-hour volume: the USDT perpetual and, where Binance lists one, the USDT spot pair of the same coin. A perpetual chart shows the perpetual book; a spot chart shows the spot book. The two are not merged into one heatmap: they are different markets with their own participants, so their walls can differ. To compare them, open both charts side by side.

How to open the heatmap in AlertaChart

1. In the AlertaChart app, open a Binance USDT chart of a large coin, perpetual or spot, for example the BTC/USDT perpetual.
2. Choose a short timeframe and zoom in. One view fills at most one hour at the full stream resolution, or six hours at one-second resolution; when it spans more, only its latest part is filled and the legend says "Latest hours of the view shown: zoom in".
3. Click Orderflow in the chart toolbar to open the Orderflow Toolbox (on a phone, it is the last entry of the Indicators list), click Order Book Heatmap and pick With candles or Bookmap under View.
4. Hover the heatmap row in the legend at the top left of the chart and press the gear to change contrast, dots or the ladder.
5. Hover the heat to read Resting and Book now at any price.

Open the BTC/USDT perpetual chart in the app; then add Order Book Heatmap from the Orderflow Toolbox →Pro

The heatmap belongs to the order-flow tools of the Pro and Elite plans (compare plans). The order-flow section of the features page shows the rest of the toolbox.

Settings that matter

Common mistakes

• Treating a bright band as support or resistance. It is an order that could be cancelled the next second.
• Comparing brightness across zoom levels. The colour scale is rebuilt for every view.
• Reading empty space as an empty book. Before AlertaChart started recording a market, and wherever the stream was lost, there is simply no data.
• Assuming the spot and perpetual books look alike.
• Missing the status line. "Live every 3 s (exchange unreachable)" means the live picture is coarser than usual.

Method and limitations

The product statements come from the app's heatmap code as of 5 October 2026; how a book update works comes from Binance's API documentation; the definition of spoofing from US law. The limits that matter most:

• Recording only. The heat exists only from the moment AlertaChart began recording a market. Gaps, for example when the stream was lost, stay empty instead of being averaged down.
• A band around the price. The recorder keeps a band of price levels around the market, so very distant orders may not appear.
• Coverage. Binance only, USDT pairs only, about 50 coins whose list follows 24-hour volume; elsewhere the legend says "Not available for this market".
• Short-lived orders. Updates arrive every 100 milliseconds; an order shown for less than a column's width of time barely colours it.
• Live data. Your browser connects to Binance directly for the live book. If that fails, the chart reads AlertaChart's copy every 3 seconds.
• Bar Replay. In replay the heatmap shows only what was recorded up to the replay time and hides the current order book ladder.
• Visible orders only. The heatmap shows what the public book showed; it cannot reveal why an order was placed or cancelled.

Related guides and pages

• Footprint chart guide: what traded at each price inside a candle.
• CVD indicator guide: the running balance of aggressive buying and selling.
• Order flow in the Help Center: every order-flow tool, including the Level 2 order book.
• Order flow on the features page: the whole toolbox at a glance.