Tag Master is a free Chrome extension that brings all your GA4 and GTM debugging tools into one side panel. - Inject GTM snippets on any page and auto-detect containers - Monitor dataLayer events with GA4 schema validation (scored 0-100) - Decode GA4, Google Ads & Floodlight network requests with consent state - Generate CSS selectors and GTM variable code visually - Manage Google tracking cookies and simulate GCLID for Ads testing No account needed. No data collection. 100% free.