// glossary
Server-Side GTM.
Server-side Google Tag Manager (sGTM)
Server-side GTM (sGTM) is a Google Tag Manager architecture that runs tags on your own server rather than the browser, recovering cookie loss, ad-blocker impact and page-speed cost. Data flows browser → your 1st-party domain → server-side fan-out to platforms.
// detail
Classic client-side GTM loads 5-10 third-party tags in the browser and sends requests directly to Google, Meta and TikTok. Three problems:
- Third-party cookie loss — Safari ITP, iOS 14.5+ ATT, ad-blockers reduce measurement by 20-40%.
- Performance — page load slows.
- Data control — every field goes to third parties; PII filtering is impossible.
sGTM solves most of this:
- Runs on Google Cloud Run (~$30-60/mo at small scale).
- 1st-party domain delivery → ITP loss drops from 20-40% to 5-10%.
- One browser tag → faster page.
- PII filtering happens server-side.
Example: An e-commerce site had a 22% gap between GA4 and Google Ads conversion counts before sGTM. After deployment the gap dropped to 6%, and Enhanced Conversions match rate climbed from 48% to 71%.