> ## Documentation Index
> Fetch the complete documentation index at: https://orderly.network/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Open interest

> Subscribe to open interest updates for a symbol via WebSocket, with 1s change and 10s forced push.

Push interval: push every 1 second if open interest change and 10 seconds force update even if no change.

```json theme={null}
{
  "id": "clientID10",
  "topic": "PERP_ETH_USDC@openinterest",
  "event": "subscribe"
}
```

**Parameters**

| Name  | Type   | Required | Description               |
| ----- | ------ | -------- | ------------------------- |
| id    | string | Y        | id generate by client     |
| event | string | Y        | `subscribe`/`unsubscribe` |
| topic | string | N        | `{symbol}@openinterest`   |

<RequestExample>
  ```json Response theme={null}
  {
     "id":"clientID10",
     "event":"subscribe",
     "success":true,
     "ts":1682242071080
  }
  ```
</RequestExample>

<ResponseExample>
  ```json Subscribed Message theme={null}
  {
     "topic":"PERP_ETH_USDC@openinterest",
     "ts":1682242080006,
     "data":{
        "symbol":"PERP_ETH_USDC",
        "openInterest":1.2741
     }
  }
  ```
</ResponseExample>