Order Book

The first push after subscribing is a full snapshot; all subsequent pushes are incremental updates. Updated every 250ms. Use seq and pre_seq to verify continuity — if pre_seq does not match the previous seq, re-subscribe to get a fresh snapshot.

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

Parameter	Required	Description
`sym`	Yes	Trading pair
`level`	No	Depth levels: `50` (default) or `200`

Push Data

Full snapshot (updatetype: "all") — sent once on subscribe:

{
    "arg": { "channel": "ORDER_BOOK", "sym": "BINANCE_PERP_BTC_USDT", "updatetype": "all" },
    "data": {
        "ts": "1597026383085",
        "seq": "1000",
        "pre_seq": "0",
        "num": 1,
        "Bids": [["70283.2", "0.004"], ["70282.8", "0.005"]],
        "Asks": [["70296.1", "0.095"], ["70296.2", "0.126"]]
    }
}

Incremental update (updatetype: "update") — all subsequent pushes:

{
    "arg": { "channel": "ORDER_BOOK", "sym": "BINANCE_PERP_BTC_USDT", "updatetype": "update" },
    "data": {
        "ts": "1597026384085",
        "seq": "1001",
        "pre_seq": "1000",
        "num": 2,
        "Bids": [["70286.8", "0.004"]],
        "Asks": [["70287.6", "0.538"]]
    }
}

Field	Description
`updatetype`	`all` = full snapshot, `update` = incremental
`seq`	Current sequence number
`pre_seq`	Previous sequence number
`num`	Cumulative push count
`Bids` / `Asks`	`[price, quantity]` pairs
`ts`	Timestamp (ms)

Subscribe

Push Data