Tape - live WebSocket - BackQuant API

wss://api.backquant.com/v2/ws/options Single connection, multiple subscriptions. The same canonical trade payload from the REST tape, pushed sub-second after the upstream venue emits it.

Authentication

Pass your API key on the WebSocket handshake - either of:

Query parameter - wss://api.backquant.com/v2/ws/options?api_key=bq_live_... (easiest from browsers).
Authorization: Bearer header - preferred from server-to-server clients.
X-API-Key header - accepted as a fallback for clients that can set arbitrary handshake headers.

The handshake validates the key, subscription status and tier eligibility. Failures close the connection with a 1008 policy-violation code and a human-readable reason.

Channel inventory

Channel	Payload	Frequency
`tape.{coin}.{venue}`	One trade per frame	Per trade (~10-100/s in burst)
`tape.{coin}.agg`	Same trade payload, aggregated across all venues for that coin	Per trade
`gex.levels.{SYMBOL}`	FLOW-signed GEX levels (all-expiry + 0DTE HVL, walls, spot)	When levels update (~30 s)
`status.heartbeat`	Server liveness + per-client queue stats	Every 15 s

{coin} is typically BTC or ETH (SOL/HYPE appear when tape exists). {venue} is one of deribit, bybit, okx, binance, derive, thalex, delta_india, delta (case-insensitive on subscribe; the server normalises to lowercase). {SYMBOL} is BTCUSDT, ETHUSDT, SOLUSDT, or HYPEUSDT. See Venue coverage for what each venue ships. Levels note (changed in 2.6.0): gex.levels.* pushes flow-signed levels - the same model and the same builder as REST /v2/gex/levels, so the two surfaces always agree. Before 2.6.0 this channel pushed a std (textbook) snapshot while REST defaulted to flow. When the aggressor tape is unavailable for a symbol the payload falls back to the worker’s std snapshot and says so: positioning: "std" plus a fallback_reason. Always read positioning before overlaying the numbers on anything else. See Positioning. On subscribing to gex.levels.* the server sends the current levels immediately, flagged "snapshot": true, then pushes again only when the levels move. Without that first frame you could not tell an idle book from a subscription that never took. Max 48 channels per connection.

Protocol

Server → client envelope

Every server frame is a JSON object with an event field:

{ "event": "welcome",       "ts": "...", "subscription_tier": "enterprise",
                            "client_id": "abc...", "max_channels": 48,
                            "available_channels": [...] }

{ "event": "subscribed",    "ts": "...", "channels": [...], "added": [...] }
{ "event": "unsubscribed",  "ts": "...", "channels": [...], "removed": [...] }

{ "event": "trade",         "ts": "...", "channel": "tape.BTC.deribit",
                            "data": { ...trade payload... } }

{ "event": "levels",        "ts": "...", "channel": "gex.levels.BTCUSDT",
                            "data": { "symbol": "BTCUSDT", "spot_price": ...,
                                      "all_expiry": { "hvl": ..., "call_resistance": ...,
                                                      "put_support": ...,
                                                      "call_wall_2": null, "call_wall_3": null,
                                                      "put_wall_2": null, "put_wall_3": null },
                                      "odte": { "hvl": ..., "call_resistance": ...,
                                                "put_support": ... },
                                      "positioning": "flow", "fallback_reason": null,
                                      "ts": "...", "positioning_note": "..." } }

{ "event": "heartbeat",     "ts": "...", "channel": "status.heartbeat",
                            "queue": { "size": 7, "capacity": 1000 },
                            "channels": ["tape.BTC.agg", ...] }

{ "event": "pong",          "ts": "..." }
{ "event": "error",         "ts": "...", "detail": "...",
                            "invalid": [...], "available_channels": [...] }
{ "event": "slow_consumer", "ts": "...", "detail": "Queue full for >5s ..." }

Client → server commands

{ "action": "subscribe",   "channels": ["tape.BTC.agg", "gex.levels.BTCUSDT"] }
{ "action": "unsubscribe", "channels": ["tape.BTC.deribit"] }
{ "action": "ping" }

Each command receives a corresponding ack frame.

Trade payload

{
  "venue":          "deribit",
  "coin":           "BTC",
  "instrument":     "BTC-30JUN26-100000-C",
  "trade_id":      "12345",
  "direction":      "buy",
  "option_type":    "call",
  "strike":         100000.0,
  "expiry_date":    "2026-06-30",
  "amount":         1.5,
  "price":          0.0525,
  "mark_price":     0.0530,
  "index_price":    67234.10,
  "iv":             65.4,
  "premium_usd":    5293.60,
  "is_block_trade": false,
  "ts_ms":          1748480000000
}

Field	Meaning
`venue`	`deribit` \| `bybit` \| `okx` \| `binance` \| `derive` \| `thalex` \| `delta_india` \| `delta`
`amount`	Coin-equivalent size (normalized at ingest)
`price`	Venue-quoted price (units vary by venue)
`premium_usd`	Canonical USD premium - rank and filter on this

amount and premium_usd are comparable across venues. For Delta ingest details see Venue coverage → Delta units.

Connection lifecycle

Connect with API key → server validates → counts connection against your per-tier cap.
Receive welcome → sanity-check subscription_tier and available_channels.
Send subscribe → server replies with subscribed ack + immediately starts streaming matching trades.
Stream - trades arrive on their channel; status.heartbeat arrives every 15 s if subscribed.
Heartbeat liveness - the server expects at least one client frame (subscribe / unsubscribe / ping) within 60 s. Otherwise it closes with code 1001.
Slow consumer - each client has a 1000-message send buffer. If full for > 5 s the server sends a slow_consumer event then closes with code 1013. Reduce your subscription set or process frames faster.
Disconnect → connection counter decrements; reconnect any time.

Per-tier connection caps

Level	Concurrent WS connections
Starter	1
Standard	2
Pro	5
Enterprise	up to 25 (custom)

Exceeding the cap on connect returns close code 1008 with a connection-cap message. WS usage does not draw down monthly REST quota - see Rate limits.

Reconnect template

The server has no replay - $ cursor is used on the underlying Redis stream, so a reconnect resumes with whatever’s live, not whatever you missed. For zero-gap consumers, also poll /v2/tape?after=<last_ts> on reconnect to fetch trades that arrived during the gap.

import asyncio, json, os, random, websockets

URL = "wss://api.backquant.com/v2/ws/options?api_key=" + os.environ["BQ_API_KEY"]
CHANNELS = ["tape.BTC.agg", "status.heartbeat"]

async def run():
    attempt = 0
    while True:
        try:
            async with websockets.connect(URL, ping_interval=20) as ws:
                await ws.recv()  # welcome
                await ws.send(json.dumps({"action": "subscribe", "channels": CHANNELS}))
                attempt = 0
                async for raw in ws:
                    msg = json.loads(raw)
                    if msg.get("event") == "trade":
                        handle(msg["data"])
        except (websockets.ConnectionClosed, ConnectionError) as e:
            attempt += 1
            backoff = min(60, 2 ** attempt) * (1 + random.uniform(-0.2, 0.2))
            print(f"reconnect in {backoff:.1f}s ({e})")
            await asyncio.sleep(backoff)

def handle(trade):
    print(trade["venue"], trade["instrument"], trade["direction"], f"${trade['premium_usd']:,.0f}")

asyncio.run(run())

Full working client: scripts/v2_ws_demo/ws_tape_demo.py.

Get Started

Concepts

Code examples

API: Discovery & Meta

API: GEX

API: Options chain & OPEX

API: IV analytics

API: Probability density

API: Greeks

API: Open interest & flow

API: Futures & liquidation

API: Multi-symbol

API: Tape & WebSocket

Tape - live WebSocket

Authentication

Channel inventory

Protocol

Server → client envelope

Client → server commands

Trade payload

Connection lifecycle

Per-tier connection caps

Reconnect template

See also

REST tape with filters

Tape overview

GEX levels (REST, flow default)

Authentication

​Authentication

​Channel inventory

​Protocol

​Server → client envelope

​Client → server commands

​Trade payload

​Connection lifecycle

​Per-tier connection caps

​Reconnect template

​See also

REST tape with filters

Tape overview

GEX levels (REST, flow default)

Authentication

Authentication

Channel inventory

Protocol

Server → client envelope

Client → server commands

Trade payload

Connection lifecycle

Per-tier connection caps

Reconnect template

See also