> ## 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.

# Event Volume Spike

> Fire a webhook when an event's aggregated volume surges past its recent baseline.

<Note>
  **Event:** `event_volume_spike` \
  **Cost:** 0.2 credits per delivery
</Note>

The `event_volume_spike` event fires when an event's aggregated volume in a timeframe exceeds its recent baseline by your spike ratio. The full payload schema is in the auto-generated [Event Volume Spike callback](/api-reference/webhook-callbacks/event-volume-spike-callback) reference; this page documents the filters and matching behavior.

## When to use this

* Detect activity surges across all markets in an event at once.
* Tune sensitivity by setting how far aggregated volume must exceed its baseline.
* Compare event-level activity across multiple timeframes in a single subscription.

## Subscription filters

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

| Filter                      | Type      | Description                                                                               |
| --------------------------- | --------- | ----------------------------------------------------------------------------------------- |
| `spike_ratio`               | number    | Volume must exceed its baseline by at least this ratio (must be greater than `1.0`).      |
| `window_secs`               | integer   | Look-back window in seconds (`1`–`600`).                                                  |
| `event_slugs`               | string\[] | Restrict to specific events by slug (max 500).                                            |
| `timeframes`                | string\[] | One or more windows: `1m`, `5m`, `30m`, `1h`, `6h`, `1d`, `24h`, `7d`, `30d`, `lifetime`. |
| `exclude_shortterm_markets` | boolean   | Exclude short-term Up/Down markets.                                                       |

## Example

```json theme={null}
{
  "url": "https://your-server.com/webhooks",
  "event": "event_volume_spike",
  "filters": {
    "spike_ratio": 2.5,
    "window_secs": 600,
    "timeframes": ["1h"]
  }
}
```

## Notes

* `spike_ratio` must be greater than `1.0`; for example `3.0` means 3x the recent baseline.