What is free
Google publishes an account anomaly detector script for Google Ads under Apache 2.0. It compares today with the same weekday history and emails an alert, with one alert a day per type. GA4 also has built-in anomaly detection on time series.
What a set-up adds
A free script needs bands that suit your spend, an owner and a backup who will see the alert, and proof that it would have caught a past incident. Set the bands on the first 60 days of history, test them on the last 30, and cap the false alerts per month. Use the read-only access level, which cannot edit campaigns, and check that an edit attempt fails.
- Same-weekday baseline.
- A named owner and a backup.
- Read-only access that is tested.
What it cannot do
An alert is not a pause. Pausing a campaign is a decision for a person. Google Ads data can be up to 3 hours late and standard GA4 data 24 to 48 hours late, so these alerts are not real time.
Sources and limits
- Google Ads: account anomaly detector script Checked 2026-10-12.
- A free sample script under Apache 2.0 compares today with the same weekday history and emails an alert, with one alert a day per type.
- Google Analytics: anomaly detection Checked 2026-10-12.
- GA4 has built-in anomaly detection on time series.
- Google Ads: access levels Checked 2026-10-12.
- The read-only access level cannot edit campaigns; the Standard and Admin levels can.
- Google Analytics: data freshness Checked 2026-10-12.
- Google says GA4 data processing can take 24 to 48 hours.