---
title: "Event format | Binance Open Platform"
source: "https://developers.binance.com/docs/binance-spot-api-docs/websocket-api/event-format"
fetched_at: "2026-02-26T10:38:12.736Z"
---
[User Data Stream](https://developers.binance.com/docs/binance-spot-api-docs/user-data-stream) events for non-SBE sessions are sent as JSON in **text frames**, one event per frame.

Events in [SBE sessions](https://developers.binance.com/docs/binance-spot-api-docs/faqs/sbe_faq) will be sent as **binary frames**.

Please refer to [`userDataStream.subscribe`](https://developers.binance.com/docs/binance-spot-api-docs/websocket-api/user-data-stream-requests) 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](https://developers.binance.com/docs/binance-spot-api-docs/user-data-stream)

`subscriptionId`

INT

NO

Identifies which subscription the event is coming from. See [User Data Stream subscriptions](https://developers.binance.com/docs/binance-spot-api-docs/websocket-api/event-format)