Preview & Debug

Test your server-side setup safely using GTM Preview and Tag Assistant against a separate preview environment that never touches your live data.

Every Pixel Logic Server includes a separate preview environment, so you can inspect and debug your tags without affecting the data your live visitors generate. Production and preview are fully isolated.

How debugging server-side works

When you click Preview on your GTM Server container, GTM connects to your server's preview environment and shows you, request by request, exactly what arrives and which tags fire. Combined with Tag Assistant on the web side, you get the full picture: browser → server → destinations.

  ┌──────────────────────────┐
  │  Tag Assistant            │
  │  (your browser)           │
  │  debug a page view        │
  └────────────┬─────────────┘
               │
               ▼
  ┌──────────────────────────┐
  │  Preview environment      │
  │  your server, preview mode│
  │  (isolated from live)     │
  └────────────┬─────────────┘
               │
               ▼
  ┌──────────────────────────┐
  │  You see                  │
  │  • each incoming event    │
  │  • which tags fired       │
  │  • the data sent onward   │
  │  • errors, if any         │
  └──────────────────────────┘

Step-by-step

  1. In GTM, open your Server container and click Preview.
  2. Open your website in the same browser. Tag Assistant will connect the two.
  3. Trigger events on your site (page views, clicks, a test purchase).
  4. In the GTM preview pane, watch each event arrive and confirm your GA4 (and any other) tags fire with the right data.
  5. When everything looks right, Publish your server container.

Tips

  • Publish after debugging. Preview shows unpublished changes; your live visitors only get what you've published.
  • Use a realistic path. Debug with the same browser/device mix your audience uses so you catch Safari/ITP and consent behavior.
  • Purge the cache after publishing. If you changed your web GTM container, use Purge Cache on your container page so the new version is served right away — see Manage Your Server.

A note on ad-blocker testing

Tag Assistant and GTM Preview work with the Pixel Logic URL (Mode 1) and your own domain (Mode 2). They are debugging tools and bypass some of the protections that make production resistant to blockers, so always do a final check on your published, real-world setup — not just in preview.