ritmex-bot/docs/binance/binance-spot/testnet_websocket-api_event-format.md

title, source, fetched_at

title	source	fetched_at
Event format | Binance Open Platform	https://developers.binance.com/docs/binance-spot-api-docs/testnet/websocket-api/event-format	2026-02-26T10:38:11.531Z

User Data Stream events for non-SBE sessions are sent as JSON in text frames, one event per frame.

Events in SBE sessions will be sent as binary frames.

Please refer to userDataStream.subscribe for details on how to subscribe to User Data Stream in WebSocket API.

Example of an event:

{    "subscriptionId": 0,    "event": {        "e": "outboundAccountPosition",        "E": 1728972148778,        "u": 1728972148778,        "B": [            {                "a": "BTC",                "f": "11818.00000000",                "l": "182.00000000"            },            {                "a": "USDT",                "f": "10580.00000000",                "l": "70.00000000"            }        ]    }}

Event fields:

Name

Type

Mandatory

Description

event

OBJECT

YES

Event payload. See User Data Streams

subscriptionId

INT

NO

Identifies which subscription the event is coming from. See User Data Stream subscriptions