chorus_strength

Sent when the chorus's strength (the CHORUS panel's -100 to 100 reading of how far the counted sets move together with SPX or NDX) reaches your chosen size, up or down.

POSTyour https addressX-FirmTape-Event: chorus_strength

Plan LIVEPayload version 1Signed HMAC-SHA256Schema chorus_strength.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 a chorus card on with its size, the symbol SPX or NDX on that card.

When it is sent

Read on each closed minute of the chorus of the symbol on the card, SPX or NDX.
Each size and way fires once, then re-arms only after the strength has fallen back under 20 that way.
The first minute of a day only arms: a day that opens past the size sends nothing until it re-arms.

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"chorus_strength"	`chorus_strength`.
symbolstring	SPX, ES, NQ, RTY or a ticker.
levelobject	The level the event is about.
level.kindflip \| call_wall \| put_wall \| net_gamma \| price \| cvd \| level_of_interest \| chorus \| null	`flip`, `call_wall`, `put_wall`, `net_gamma`, `price` for a price line, `level_of_interest` for C1 to C4 and P1 to P4 (with `rank`), `cvd` for a CVD line (its value in contracts of calls minus puts in one bar), or `chorus` for the chorus's strength (its value from -100 to 100).
level.valuenumber \| null	Its value at the event.	index points
level.fromnumber \| null	Moves: where it stood before.	index points
level.rankstring	Levels of interest: the rank, `C1` to `C4` or `P1` to `P4`, as on the chart.
pricenumber \| null	The price at the event. Null on a `premarket` event (see `phase`).	index points
bookvolume \| open_interest \| measured \| volume+open_interest	The book the event was read in, as the account picked it for that card: `volume`, `open_interest`, `measured` (SPX, ES, NQ), or `volume+open_interest` (levels of interest only, as on the chart). A symbol without the book picked is read in `volume`.
tsstring	When it was found, ISO 8601 in New York time.
daystring	The ET trading day.
levelsobject	The flip and the walls of the book in `book` at the event (the volume book's for `volume+open_interest`).
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.
directionup \| down	The way the strength reached the size: `up` at +size or above, `down` at -size or below.
threshold_pointsnumber	Sized events (`flip_move`, `level_near`, `interest_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.
phasepremarket	Present only when a price line fired before the bell, from 04:00 ET to the open on a trading day: `premarket`. The line was crossed on the premarket's minute prices; `price` is then null, and `levels` are the previous session's closing levels. Absent on every event in the session.
alertobject	Alert lines only: the line that fired.
alert.idstring	The line, `al_...`.
alert.kindstring	`price`, `level` or `delta` (a CVD line).
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`.
joinsarray	One event for several levels on one price (a wall and levels of interest): the types it stands for, e.g. `["wall_break", "interest_cross"]`.
thresholdnumber	The size you picked: 40, 60 or 80, a strength, not points.
setsobject	The counted sets at that minute: how many move in unison up, down, how many go against the index, and how many are counted.
sets.upinteger
sets.downinteger
sets.againstinteger
sets.ofinteger \| null

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.

flip_cross · wall_break · regime_change · wall_move · flip_move · level_near · interest_new · interest_move · interest_drop · interest_cross · interest_near · price_alert · level_line · cvd_line · order · test

Request we send

POST https://your.server/firmtape
Content-Type: application/json
User-Agent: FirmTape-Webhooks/1
X-FirmTape-Event: chorus_strength
X-FirmTape-Event-Id: evt_8b21d4c0e7f93a6512cd04ab
X-FirmTape-Timestamp: 1760034725
X-FirmTape-Signature: sha256=9b1e...

Body

{
  "version": 1,
  "id": "evt_8b21d4c0e7f93a6512cd04ab",
  "type": "chorus_strength",
  "symbol": "SPX",
  "level": {
    "kind": "chorus",
    "value": -43
  },
  "price": 6731.5,
  "book": "volume",
  "ts": "2026-10-22T10:21:04-04:00",
  "day": "2026-10-22",
  "levels": {
    "flip": 6745.5,
    "call_wall": 6800,
    "put_wall": 6700,
    "put_support": 6700
  },
  "text": "SPX CHORUS ▼ strength 43, past 40 · 4 of 8 sets down · 10:20 ET",
  "direction": "down",
  "threshold": 40,
  "sets": {
    "up": 0,
    "down": 4,
    "against": 1,
    "of": 8
  }
}

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/chorus_strength.md.

chorus_strength

When it is sent

Payload

Delivery

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