Zero-DTE Heatmap API

Endpoint

GET /v1/flow/zero-dte/heatmap/{symbol}

Auth required (X-Api-Key) Rate Limited: Yes Alpha plan+

Parameters

Name	In	Required	Default	Description
`symbol`	path	yes	-	Underlying symbol. Trimmed and upper-cased.
`metric`	query	no	`gex`	Per-strike value to project. One of `gex`, `dex`, `vex`, `chex`, `oi`, `signed_flow`. Invalid returns 400 invalid_metric.
`mode`	query	no	`raw`	`raw` (absolute per-bar value) or `delta` (bar-over-bar change; bar 0 stays raw). For `signed_flow`, delta is equivalent to raw. Invalid returns 400 invalid_mode.
`bar`	query	no	`1m`	Bar size. Only `1m` is supported in this phase (5m/15m are planned); any other value returns 400 bar_unavailable.
`minutes`	query	no	`60`	Lookback window in minutes. Clamped to 1-390.

curl -H "X-Api-Key: YOUR_API_KEY" \
  "https://lab.flashalpha.com/v1/flow/zero-dte/heatmap/SPY?metric=gex&mode=raw&bar=1m&minutes=120"

import requests

resp = requests.get(
    "https://lab.flashalpha.com/v1/flow/zero-dte/heatmap/SPY",
    params={"metric": "gex", "mode": "raw", "bar": "1m", "minutes": 120},
    headers={"X-Api-Key": "YOUR_API_KEY"}
)
data = resp.json()
print(data["strikes_grid"])

const resp = await fetch(
  "https://lab.flashalpha.com/v1/flow/zero-dte/heatmap/SPY?metric=gex&mode=raw&bar=1m&minutes=120",
  { headers: { "X-Api-Key": "YOUR_API_KEY" } }
);
const data = await resp.json();
console.log(data.strikes_grid);

API Key

Response

{
  "symbol": "SPY",
  "underlying_price": 590.42,
  "expiration": "2026-06-05",
  "metric": "gex",                     // echoes the requested metric
  "mode": "raw",                       // echoes the requested mode
  "bar_size": "1m",                    // echoes the requested bar
  "as_of": "2026-06-05T18:45:12Z",     // UTC
  "tier_used": "raw",
  "strikes_grid": [585, 586, 587, 588, 589, 590, 591, 592, 593, 594, 595],
  "bars": [
    {
      "t": "2026-06-05T18:44:00Z",     // bar timestamp (UTC)
      "spot": 590.42,
      "values": [ -1.2e8, -9.0e7, -4.1e7, 0, 3.3e7, 8.1e8, 2.2e8, 1.1e8, 4.0e7, 1.0e7, -5.0e6 ]
      // values[i] is the metric for strikes_grid[i]
    }
    // ... ascending by t
  ],
  "gap_intervals": []                  // reserved for sampler-gap intervals; not yet populated
}

No 0DTE samples in the window returns 200 with empty strikes_grid and bars arrays - there is no no_zero_dte / session_closed envelope.

Key Response Fields

Field	Type	Description
`underlying_price`	number	Current underlying spot
`expiration`	string	Today's 0DTE expiry (ET)
`metric`	string	Echoes the requested metric
`mode`	string	Echoes the requested mode (`raw` / `delta`)
`bar_size`	string	Echoes the requested bar size
`as_of`	string	Server time the response was built (UTC)
`tier_used`	string	Storage tier the data was read from
`strikes_grid`	array	Strikes for the matrix; `values[i]` maps to `strikes_grid[i]`
`bars[].t`	string	Bar timestamp (UTC)
`bars[].spot`	number	Underlying spot at the bar
`bars[].values`	array	Per-strike metric values, parallel by index to `strikes_grid`
`gap_intervals`	array	Reserved for sampler-gap intervals; not yet populated

Errors

Status	Description
`400`	`bar_unavailable` - `bar` is anything other than 1m
`400`	`invalid_metric` - `metric` not in gex\|dex\|vex\|chex\|oi\|signed_flow
`400`	`invalid_mode` - `mode` is not raw/delta
`400`	`no_strike_data_for_window` - rows exist in the window but none carry per-strike data (legacy v1 rows)
`403`	`tier_restricted` - caller is below the Alpha plan

About

The heatmap endpoint returns a per-strike value matrix over today's 0DTE session - the data behind a strike-by-time heatmap. Strikes are pulled into a top-level strikes_grid and each bar carries a values array that is parallel by index to strikes_grid (i.e. values[strike_idx]), the column-major shape every heatmap charting library expects.

Choose the projected metric with metric (GEX, DEX, VEX, CHEX, OI, or signed flow) and switch between absolute values and bar-over-bar change with mode.

Common Use Cases

Render a strike-by-time heatmap directly from strikes_grid and the per-bar values array, the column-major shape charting libraries expect
Switch the projected layer with metric across gex, dex, vex, chex, oi, and signed_flow to read whichever exposure drives your setup
Use mode=delta to highlight where exposure is building or unwinding minute over minute rather than its absolute level
Track how the brightest cells (walls and concentrations) migrate across strikes_grid as spot moves, anticipating the next support or resistance
Watch the row nearest underlying_price for the ATM strike most likely to act as the closing pin magnet
Spot a sign flip in a strike's values over time as the bar where that level switches from supportive to repellent dealer positioning

Complementary endpoints

Zero-DTE Strike Flow - the single-strike time series behind one heatmap row
Zero-DTE Flow Series - the aggregate headline metrics across the same session
Flow Levels - the named walls and magnet the heatmap visualizes