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

# Cost Anomaly Detection

> Beacon monitors your AWS spend continuously and alerts you when something unusual happens.

## How it works

OpsBeacon compares your current spend patterns against your historical baseline. When a service, account, or tag group spends significantly more than expected, Beacon flags it as an anomaly and posts an alert to your Slack channel.

## What triggers an alert

* A service spend that is more than 2x its 7-day average
* A new service appearing in your bill that wasn't there before
* A single-day cost spike exceeding a configurable threshold
* Month-to-date spend on track to exceed your budget

## Asking about anomalies

```
@Beacon any cost anomalies this week?
@Beacon what caused the spike yesterday?
@Beacon is there anything unusual in my bill?
```

## Automatic alerts

Beacon can post anomaly alerts automatically as they're detected. To enable:

```
@Beacon alert me in this channel when there's a cost spike
```

## Root cause analysis

When Beacon flags an anomaly, it includes a root cause breakdown — which specific resources, regions, or usage types drove the change. See [Cost Drivers & Root Cause Analysis](https://docs.opsbeacon.co/cost-intelligence/cost-drivers-root-cause.md) for more detail.


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