Overview

Real-time market data via WebSocket. Subscribe to order books, trades, tickers, prices, candlesticks, and open interest across supported exchanges.

WebSocket URL: wss://md.liquiditytech.com/marketdata/v2/public

Supported exchanges: BINANCE / OKX / EDX

Connection

Responses are GZIP-compressed by default. To receive plain text, append ?binary=false to the URL:

wss://md.liquiditytech.com/marketdata/v2/public?binary=false

To decompress in Python:

import zlib

# binary_data is the raw bytes received from ws.recv()

decompressed = zlib.decompress(binary_data, zlib.MAX_WBITS | 16).decode('utf-8')

Authentication

Authentication is optional. Unauthenticated connections work immediately but have lower rate limits.

To authenticate, send a login message after connecting and before subscribing

{
    "action": "login",
    "args": {
        "apiKey": "your_api_key",
        "timestamp": "1597026383085",
        "sign": "your_signature"
    }
}

Note: the login message uses "action" and "args" (an object), while subscribe/unsubscribe messages use "event" and "arg" (an array). These are different field names.

Signature: HMAC-SHA256(secret, timestamp + "GET" + "/users/self/verify"), hex-encoded.

import hmac, hashlib, time

api_key = "your_api_key"
secret  = "your_secret_key"

timestamp = str(int(time.time()))
message = timestamp + "GET" + "/users/self/verify"
sign = hmac.new(secret.encode(), message.encode(), hashlib.sha256).hexdigest()

Response:

{ "event": "login", "code": "200000", "msg": "success" }

Rate Limits

	Unauthenticated	Authenticated
Max connections per IP	5	40
Max trading pairs per connection	5	50

Subscription rate: max 50 subscribe/unsubscribe requests per second per IP. Exceeding this returns error 11260.

Limits are counted by trading pair, not by channel. Subscribing to TICKER, ORDER_BOOK, and TRADE for the same symbol counts as 1 trading pair.

Heartbeat

The server sends a WebSocket protocol-level ping shortly after the connection is established. Most WebSocket client libraries handle this automatically.

The connection is closed if the client is inactive for 60 seconds. To keep the connection alive, the client must send a JSON ping at regular intervals (recommended: every 20 seconds):

The client can also send a ping at any time:

{ "ping": 1769050973831 }

Server response:

{ "pong": 1769050974552 }

For subscribed connections receiving frequent pushes (e.g. TICKER, BBO), the data flow itself keeps the connection alive. Explicit pings are only required when subscribed to low-frequency or no channels.

Symbol Format

Symbols follow the pattern {EXCHANGE}_{TYPE}_{BASE}_{QUOTE}:

Part	Values	Example
`EXCHANGE`	`BINANCE` / `OKX` / `EDX`	`BINANCE`
`TYPE`	`SPOT` / `PERP` (perpetual futures)	`PERP`
`BASE`	Base currency	`BTC`
`QUOTE`	Quote currency	`USDT`

Examples: BINANCE_PERP_BTC_USDT, OKX_SPOT_ETH_USDT

Futures-only channels (MARK_PRICE, INDEX_PRICE, OPEN_INTEREST, etc.) require a PERP symbol. Using a SPOT symbol with these channels returns error 11100.

Subscribe & Unsubscribe

Multiple channels can be included in a single request.

Subscribe:

{
    "event": "subscribe",
    "arg": [
        { "channel": "TICKER", "sym": "BINANCE_PERP_BTC_USDT" },
        { "channel": "ORDER_BOOK", "sym": "OKX_SPOT_ETH_USDT", "level": 50 }
    ]
}

Unsubscribe:

{
    "event": "unsubscribe",
    "arg": [
        { "channel": "TICKER", "sym": "BINANCE_PERP_BTC_USDT" }
    ]
}

Success response:

{
    "event": "subscribe",
    "arg": [{ "channel": "TICKER", "sym": "BINANCE_PERP_BTC_USDT" }],
    "code": 0,
    "message": "Success"
}

Failure response:

{
    "event": "subscribe",
    "arg": [{ "channel": "TICKER", "sym": "INVALID_SYM" }],
    "code": 11100,
    "message": "invalid symbols"
}

All channel names must be uppercase. Using lowercase returns error 11103.

Available Channels

Channel	Description	Push Frequency	Scope
`TICKER`	24-hour rolling ticker	2000ms	All
`ORDER_BOOK`	Order book depth	250ms	All
`BBO`	Best bid & offer	On change	All
`TRADE`	Latest trades	Real-time	All
`MARK_PRICE`	Mark price	Real-time	Futures only
`INDEX_PRICE`	Index price	Real-time	Futures only
`KLINE`	Candlestick (trade price)	Real-time	All
`INDEX_KLINE`	Candlestick (index price)	Real-time	Futures only
`MARK_PRICE_KLINE`	Candlestick (mark price)	Real-time	Futures only
`OPEN_INTEREST`	Contract open interest	Real-time	Futures only

Error Codes

Code	Description
`200000`	Login successful
`11100`	Invalid symbol
`11101`	Invalid candlestick interval
`11102`	Invalid event type
`11103`	Invalid channel name (must be uppercase)
`11106`	Unknown protocol version
`11107`	Depth data not found
`11108`	Response too long
`11109`	Too many symbols subscribed
`11112`	Invalid depth level
`11200`	Invalid request parameter
`11210`	Exceeded 5-symbol limit (unauthenticated)
`11220`	Exceeded 50-symbol limit (authenticated)
`11230`	Exceeded 5-connection limit (unauthenticated)
`11240`	Exceeded 40-connection limit (authenticated)
`11250`	Symbol not currently supported
`11260`	Exceeded 50 requests/second limit