TagAudit's free scan finds the Google Tag Manager containers (GTM-), GA4 measurement IDs (G-) and Google Ads tags (AW-) it can see in a site's page source and network traffic. It flags more than one GA4-shaped ID on the page you scan, and a consent platform with GA4 or an ad tag but no Consent Mode signal.
How do I check if Google Tag Manager is installed on a website?
Enter the address. The scan reads the page source and the browser's network requests and lists every GTM container ID it finds, together with any GA4 and Google Ads IDs. You need no access to the client's Google accounts and no browser extension.
What this can't tell you
- Whether a tag fired. Finding an ID in the page is a sign the tag is there, not proof. The consent section shows the requests tags made.
- Property settings. Without access to the Google account, the scan sees no retention, filters or conversions settings.
- Inside a server-side container. The scan can spot a server-side tagging endpoint but cannot see what it forwards.