A candle tells you four numbers. Open, high, low, close. Everything that happened inside it, the sixty seconds of buyers hitting offers and sellers refusing to move, is thrown away. Order flow tools are attempts to keep some of that detail, and they split into three families: footprints, delta, and heatmaps.
They are useful. They are also the most oversold category of software a retail trader will ever be shown, mostly because the vendors selling them rarely explain what data the tool is built on.
Footprint charts: the candle with its insides showing
A footprint chart takes each bar and prints, at every price level inside it, how much traded at the bid and how much traded at the ask. Instead of one green body you get a column of numbers, two per row.
The classification is mechanical. A trade that prints at the offer is counted as buy-initiated, a trade at the bid as sell-initiated. That is a convention, not a truth: a seller who wants out immediately lifts the offer, and gets counted as a buyer. The number tells you which side was crossing the spread, which is a decent proxy for urgency and a poor proxy for intent.
What people look for is imbalance. A price level where ask-side volume dwarfs bid-side volume by some ratio, stacked over several consecutive levels, marks where aggressive buying pushed through. When a move stalls and the imbalances flip at the extreme, that is the reading traders act on. It fails often enough that it belongs in a plan with a stop, not as a signal on its own.
Delta and cumulative delta
Delta is the same classification collapsed to one number: ask volume minus bid volume, per bar. Cumulative delta runs a running total across the session, and it is usually plotted as a line under the price chart.
Delta is most interesting when it disagrees with price. Price makes a new high, cumulative delta does not, and the inference is that the push was thin: fewer aggressive buyers were required, so the high is less defended. The opposite pattern at a low is read the same way. This is the one order flow reading I would keep if I had to drop the rest, because it is cheap to compute and it is a genuine second opinion on a break rather than a restatement of the price chart.
The trap is scale. Delta is a volume measure, so it is only comparable within an instrument and within a session. Comparing gold's delta to an index future's delta is meaningless, and comparing this morning's to a public holiday's is nearly as bad. Read it in the context of the session you are in.
Heatmaps and resting liquidity
Footprints and delta describe trades that happened. A heatmap describes orders that are waiting. It records the visible book over time and paints resting size as colour intensity, so a large bid parked twenty ticks below the market shows up as a bright horizontal band that persists until it is filled or pulled.
What the picture is good at is showing you where size sat and when it disappeared. Bands that vanish the moment price approaches were never going to absorb anything. Bands that get eaten and hold tell you an actual transfer took place. This is the same information a depth of market ladder shows in the present tense, with history attached.
A heatmap only paints orders that were displayed. Iceberg orders, hidden size and anything handled away from the visible book do not appear, so an empty-looking level is not proof that nobody is there.
Where the data comes from, and why FX is different
All of this assumes a central order book with a consolidated tape. Futures markets have one: every contract trades on a single exchange, so volume figures are the real thing and every participant sees the same book.
Spot FX has no such venue. It is a distributed market of banks and electronic venues, and your broker shows you its own aggregated feed. What a CFD platform reports as volume is tick volume, the count of price updates, not contracts. It correlates with real activity well enough to be informative about relative intensity, and it is not a measure of size. Delta calculated on tick volume is a coarse instrument, and a heatmap on a single provider's book shows one provider's liquidity, not the market's.
None of that makes the tools worthless in FX. It makes the claims about them worth discounting. If you want order flow with a real tape behind it, you are looking at futures on a regulated exchange, and that is a different account, different sizing and different costs.
Using it without overfitting
The failure mode with order flow is not that it does not work, it is that it produces so much detail that you can always find a reason. Every bar has an imbalance somewhere. Every session has a delta divergence if you squint at a short enough window.
Anchor the tool to a location you already respected. Mark your levels on a higher timeframe first, whether that is structure or a prior session extreme, then use the flow reading only at those prices to decide whether to take the trade and where the stop sits. Flow is a confirmation layer and a timing layer. It is not a level generator, and it will not rescue a trade taken in the middle of a range.
Test it the way you would test anything else, with a record of what you saw and what happened, over a sample you did not pick after the fact. Leveraged trading carries a high risk of loss, and a more detailed chart does not change the arithmetic of position size.
"Order flow tells you how a level was defended. It never tells you which level to care about. Pick the level first."
— Roman Onta, Executive Director, SINGUARD
Key Takeaways
- Footprints classify trades by whether they hit the bid or the offer, which measures urgency rather than intent.
- Cumulative delta earns its place mainly as a disagreement signal when price makes a new extreme and delta does not.
- Heatmaps show only displayed resting orders, so hidden and iceberg size leaves no trace on them.
- Spot FX has no central tape, so delta and volume readings there are built on tick counts, not contract size.
Frequently Asked Questions
Do order flow tools work in forex?
They run on forex feeds, but the input is different. Spot FX has no central exchange, so platforms report tick volume, meaning the number of price updates rather than traded size, and depth reflects one provider's book. The readings are still relative indicators of activity, and they are not comparable to exchange-traded volume.
What is the difference between delta and cumulative delta?
Delta is ask-side volume minus bid-side volume within a single bar. Cumulative delta sums those bar values across the session as a running line, which is what makes divergences between price extremes and flow visible.
Is a footprint chart better than a normal candlestick chart?
It carries more detail inside each bar, which helps at a level you already care about and adds noise everywhere else. Most traders who use footprints still choose their levels on ordinary candlestick charts on a higher timeframe first.
About the Author
Roman Onta is an Executive Director at SINGUARD. He builds the Prop Firm CRM, the Broker CRM, Scalegram and CopySignals side by side with his brother Alex Onta, and he helped on the design of eTrader, the division Alex built and leads. His ground is worldwide payment processing, AML compliance and the corporate structures brokers are built on, work the two of them carry together, shaped by executive roles in the UAE and international corporates. He lives and works in Dubai for most of the year. Meet the executive duo leading Singuard's five divisions.