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

# Asset Price Window Update

> Fires twice per candle for a tracked asset — once when the window opens and once when it closes.

<Note>
  **Event:** `asset_price_window_update` \
  **Cost:** 0.1 credits per delivery
</Note>

Fires twice per candle for a tracked asset — once when the window opens and once when it closes. The full payload schema is in the auto-generated [Asset Price Window Update callback](/api-reference/webhook-callbacks/asset-price-window-update-callback) reference; this page documents the filters and matching behavior.

<Tip>
  **Related guide:** [Crypto Up/Down feed](/guides/crypto-up-down-feed) builds on these window open and close events to resolve Up/Down outcomes.
</Tip>

## When to use this

* Build live OHLC candles for specific assets and timeframes.
* React the moment a candle opens or closes to update charts or indicators.
* Feed windowed price data into trading signals or backtests.

## Subscription filters

Add these to the `filters` object when you create the subscription.

| Filter          | Type      | Description                                                                   |
| --------------- | --------- | ----------------------------------------------------------------------------- |
| `asset_symbols` | string\[] | Restrict to crypto assets: `BTC`, `ETH`, `SOL`, `XRP`, `DOGE`, `BNB`, `HYPE`. |
| `timeframes`    | string\[] | One or more candle sizes: `5m`, `15m`, `1h`, `4h`, `1d`, `24h`.               |

## Example

```json theme={null}
{
  "url": "https://your-server.com/webhooks",
  "event": "asset_price_window_update",
  "filters": {
    "asset_symbols": ["BTC", "ETH"],
    "timeframes": ["5m", "1h"]
  }
}
```

## Notes

* This event fires twice per candle — once when the window opens and once when it closes — so expect two deliveries per candle for each subscribed timeframe.