Google Tag Manager
intermediate
8 min read3 steps655 views

GTM Preview and Debug Mode: Complete Guide

Click Preview in GTM's top navigation, enter your website URL, and your site opens with a debug panel. The panel shows: Summary (which tags fired on each event), Tags (fired vs not fired with details), Data Layer (contents at each point), Variables (values at each event), and Errors. Test your compl

Setup & Fundamentalsgtm preview mode

Quick Summary

Click Preview in GTM's top navigation, enter your website URL, and your site opens with a debug panel. The panel shows: Summary (which tags fired on each event), Tags (fired vs not fired with details), Data Layer (contents at each point), Variables (values at each event), and Errors. Test your complete user journey: load pages, click buttons, submit forms, complete purchases. Verify every tag fires when expected and does not fire when it should not. Only publish after thorough preview testing.

Overview

Click Preview in GTM's top navigation, enter your website URL, and your site opens with a debug panel. The panel shows: Summary (which tags fired on each event), Tags (fired vs not fired with details), Data Layer (contents at each point), Variables (values at each event), and Errors. Test your complete user journey: load pages, click buttons, submit forms, complete purchases. Verify every tag fires when expected and does not fire when it should not. Only publish after thorough preview testing.

See our complete guide library for detailed coverage of setup, tracking, analysis, and optimisation across all platforms.

Process Flow

Interactive diagram — drag to pan, scroll to zoom

Step-by-Step Guide

Follow these 3 steps to complete this guide

1

Step-by-Step Setup

Access your account or platform. Navigate to the relevant section. Complete each configuration step, testing along the way. Verify your setup using built-in diagnostic tools before relying on the data for decisions.
2

Best Practices

Start with recommended defaults and optimise based on data. Review performance regularly. Make incremental changes. Document your configuration.
3

Common Issues and Solutions

Check the platform's help centre for troubleshooting. Allow 24-48 hours for data to populate. Ensure correct permissions. Verify all integrations are active and properly configured.

Frequently Asked Questions

Common questions about this topic

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