flip_cross

Sent when the price of a symbol on your watchlist crosses the volume book's zero-gamma flip and holds the new side.

POSTyour https addressX-FirmTape-Event: flip_cross

Plan LIVEPayload version 1Signed HMAC-SHA256Schema flip_cross.schema.json

This event serves

Plan: LIVE. LIVE: today's session every second, alerts, ASK, the levels API and the platform integrations, and 5 LAB credits a month. Every finished session is free in REPLAY. Pricing. Turn it on: Account, Level alerts: a webhook address, and the event on the watchlist.

When it is sent

The new side has held for twenty seconds, so a level flickering under the price says nothing.
SPX and ES: checked every five seconds against the book rebuilt every second. Other symbols: their five-minute book, named in levels_asof.
The same event is not sent again for that symbol within fifteen minutes.

Payload

Field	Meaning	Unit
version1	Payload version, `1`.
idstring	Event id, `evt_` and 24 hex digits. The same on every try and for every account the event goes to: drop one you have seen.
type"flip_cross"	`flip_cross`.
symbolstring	SPX, ES, NQ, RTY or a ticker.
levelobject	The level the event is about.
level.kindflip \| call_wall \| put_wall \| net_gamma \| price \| null	`flip`, `call_wall`, `put_wall`, `net_gamma`, or `price` for a price line.
level.valuenumber \| null	Its value at the event.	index points
level.fromnumber \| null	Moves: where it stood before.	index points
pricenumber \| null	The price at the event.	index points
bookvolume \| measured	`volume`: the volume book's levels.
tsstring	When it was found, ISO 8601 in New York time.
daystring	The ET trading day.
levelsobject	The volume book's levels at the event.
levels.flipnumber \| null	Flip.	index points
levels.call_wallnumber \| null	Call wall.	index points
levels.put_wallnumber \| null	Put wall.	index points
levels.put_supportdeprecatednumber \| null	The put wall under its first name. Deprecated: read `put_wall`; removed after 2026-11-30.	index points
textstring	The sentence Telegram and push show.
directionabove \| below	`above` or `below` the flip.
threshold_pointsnumber	Sized events (`flip_move`, `level_near`): the size the account picked, SPX points.	index points
fromstring	ES, NQ, RTY: the index whose book moved by the basis gives the levels.
basisnumber \| null	ES, NQ, RTY: the basis at the event.	index points
levels_asofstring \| null	Symbols on a five-minute book: when that book was built.
alertobject	Alert lines only: the line that fired.
alert.idstring	The line, `al_...`.
alert.kindstring	`price` or `level`.
alert.levelstring \| null	A level line: `flip`, `call_wall` or `put_wall`.
alert.pricenumber \| null	A price line: its price.	index points
alert.modestring	`once` or `repeat`.

Delivery


Answer	Any 2xx within 3 seconds. Redirects are not followed.
Retries	No answer, a 429 or a 5xx: tried again after 1 s and 4 s, three tries in all, the same id each time.
Switched off	After 10 failed events in a row; the account page shows why. Saving the address switches it on again.
Volume	Up to 30 events a minute per account; past that they are dropped and counted on the account page.
Test	`type: "test"`, from Send test
Log	The last delivery (time, status, tries) on the account page.

Verify every request before reading it: Webhooks: verify the signature.

wall_break · regime_change · wall_move · flip_move · level_near · price_alert · level_line · order · test

Request we send

POST https://your.server/firmtape
Content-Type: application/json
User-Agent: FirmTape-Webhooks/1
X-FirmTape-Event: flip_cross
X-FirmTape-Event-Id: evt_3f9a0c6e21d4b7a8e5f10c2d
X-FirmTape-Timestamp: 1760034725
X-FirmTape-Signature: sha256=9b1e...

Body

{
  "version": 1,
  "id": "evt_3f9a0c6e21d4b7a8e5f10c2d",
  "type": "flip_cross",
  "symbol": "SPX",
  "price": 6712.25,
  "book": "volume",
  "ts": "2026-10-09T14:32:05-04:00",
  "day": "2026-10-09",
  "levels": {
    "flip": 6715.5,
    "call_wall": 6750,
    "put_wall": 6700,
    "put_support": 6700
  },
  "level": {
    "kind": "flip",
    "value": 6715.5
  },
  "direction": "below",
  "text": "SPX crossed below the flip 6,715.50"
}

Verify

NodePython

const crypto = require("node:crypto");
// rawBody: the request body as received, a Buffer or a string, before any JSON parsing
function verify(rawBody, headers, secret) {
  const t = headers["x-firmtape-timestamp"];
  const got = String(headers["x-firmtape-signature"] || "");
  if (!t || Math.abs(Date.now() / 1000 - Number(t)) > 300) return false;
  const want = "sha256=" + crypto.createHmac("sha256", secret).update(`${t}.${rawBody}`).digest("hex");
  return got.length === want.length && crypto.timingSafeEqual(Buffer.from(got), Buffer.from(want));
}

import hmac, hashlib, time

def verify(raw_body: bytes, headers, secret: str) -> bool:
    t = headers.get("X-FirmTape-Timestamp", "")
    got = headers.get("X-FirmTape-Signature", "")
    if not t or abs(time.time() - int(t)) > 300:
        return False
    want = "sha256=" + hmac.new(secret.encode(), t.encode() + b"." + raw_body, hashlib.sha256).hexdigest()
    return hmac.compare_digest(got, want)

Measurements of dealer positioning, never a forecast or a trade call. This page is built from FirmTape's public contract, the same files the OpenAPI document is built from; the tests hold them against the route code. Markdown: /docs/developers/live/events/flip_cross.md.

flip_cross

When it is sent

Payload

Delivery

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