Footprint charts and what bid × ask means

On a market that publishes its trades, nothing in a footprint is inferred from the candle: the input is the exchange trade tape. The three steps between that tape and the picture are where most disagreements between platforms come from. Markets without a public tape are a separate case, and the last section covers it.

1. Read the aggressor side

Executed trades arrive with a flag saying which participant was passive. Binance publishes whether the buyer was the maker: if it was, the seller crossed the spread and the trade counts to the bid side; if it was not, the buyer crossed and it counts to the ask side. This flag is the exchange's classification, not an observation of intent, and it is what separates a "buy" from a "sell" in the tape.

2. Bucket by price

Trades are grouped into cells of a chosen tick size. Cell height is a setting, not a property of the market. Widen it and adjacent levels merge, imbalances average out and markers disappear; narrow it and the same bar sprouts dozens of thin, noisy levels. Any footprint reading is a reading at one particular bucketing.

3. Subtract

Delta is the arithmetic that follows, at cell level and at bar level. It measures the net of aggressive volume, which is not the same as net positioning: every trade still has a buyer and a seller, and delta says only which of them was in a hurry.

ask volume  = Σ size of trades where the buyer crossed the spread
bid volume  = Σ size of trades where the seller crossed the spread
cell delta  = ask volume − bid volume
bar delta   = Σ cell delta over the bar
cumulative delta (CVD) = running sum of bar delta

Each of these is a threshold applied to the cell numbers. The thresholds below are the TradersWeek defaults and all of them are adjustable in the order-flow panel; the shape of the rule is conventional across platforms, the exact numbers are not.

A footprint is evidence about the tape, and the tape is a narrower thing than the market. These are the failures worth knowing before the signal costs money, and most of them are not fixable by a better platform.

Delta is an attribution, not a measurement

It records who was impatient, not who was right or who accumulated. A market can rise on negative delta for an entire session: passive buyers absorbing aggressive sellers produce exactly that. Reading delta as demand is a common way the tool is misused.

Absorption and a vanished queue look identical

The detector sees a heavy, balanced cell. Whether a participant genuinely absorbed that flow, or a queue simply emptied and refilled from other passive orders, is not in the trade tape at all — it is in the order book, and the trade tape does not carry it. Platforms with market-by-order data see the difference; a tape-based reading infers it.

Exhaustion carries no confirmation

The rule fires on the bar itself and does not wait for the next one. This is the exhaustion candle pattern, not a validated reversal: outsized one-sided bars appear inside continuations as often as at turns. Traders who use it pair it with something on a higher timeframe, and the pairing, not the marker, is what carries the edge.

Iceberg detection is inference

Without a market-by-order feed the refill is invisible. What the detector observes is its shadow: many small aggressive trades landing on one price, heavily one-sided, price holding. That pattern also occurs when several unrelated participants queue at a round number. Calling it an iceberg is a hypothesis about the cause.

One venue is not the market

Crypto trades across many exchanges and much of the flow is on perpetual futures rather than spot. A footprint drawn from one venue's spot tape describes that venue's spot tape. It is usually a good proxy on liquid pairs and it stops being one precisely when it matters most, during a fast move that is being driven somewhere else.

Synthetic tapes are weaker evidence

Forex has no public trade tape. Platforms that show footprint on FX build prints from quote movement — the mid ticks up, that becomes a buy — or from candle volume. The chart looks identical to a crypto footprint and the evidence behind it is not. It is worth knowing which of the two you are looking at.

Footprint is one of 28 order-flow layers, computed in a Web Worker from the Binance spot trade tape rather than from candles, and drawn on the same chart as the indicators and the wave labels. The detector defaults are the numbers in the table above.

• Data: Binance spot trades, live over a WebSocket, backfilled for the visible window. Forex, metals and indices come through a MetaTrader bridge, where prints are synthesised from quotes and order flow is the weaker reading described above.
• History: the tape is loaded for the visible range, not indefinitely — 7 days on weekly bars, 48 hours on daily, 30 on hourly and above, 15 below it. Multi-year footprint replay is not covered.
• The order book is a separate panel, not the footprint: it reads the live Binance book over a WebSocket and takes limit orders by click. The chart heatmap colours executed volume inside cells, which is a different picture from a historical book heatmap.
• Price: the chart, the indicator library and automatic Elliott labeling are free without registration; footprint and the other order-flow layers are Premium at $120 per month, with no separate data bill because the Binance tape is public.