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What Is Google Tag Assistant and How to Use It
By Multivariate TeamNovember 7, 2026Analytics
Google Tag Assistant is Google's free debugging tool for the Google tag, Google Tag Manager, GA4, and Google Ads tags. It shows which tags fire on each page and what data they send, so you can catch broken tracking before it reaches your reports.
November 7, 2026
Analytics
What Google Tag Assistant does
Tag Assistant runs at tagassistant.google.com. You connect it to a page on your website, and it opens that page in debug mode. As you browse and click, it lists every event the Google tag or Tag Manager container sends, along with the tags that fired, the tags that did not, and the data layer values at each step.
It is a debugging tool, not a monitoring tool. It shows what happens in your own browser session while you test. It does not watch your live site for visitors, and debug information is not visible to them.
Google Tag Manager
Preview mode for web containers runs through Tag Assistant, so you can test changes before publishing.
GA4
See each event and parameter as it is sent, then confirm it in GA4 DebugView.
Google Ads
Check that conversion and remarketing tags fire on the right pages with the right values.
The Google tag (gtag.js)
Inspect hard-coded tags that do not use Tag Manager.
Tag Assistant, Tag Assistant Legacy, and Tag Assistant Companion
The naming has changed several times, which is why searches for Tag Assistant Legacy and Tag Assistant Companion are still common.
Tag Assistant Legacy was the original Chrome extension that showed tags on the current page. Tag Assistant Companion was a separate extension that helped the newer web-based Tag Assistant debug pages more reliably. Google has since combined both into one Tag Assistant Chrome extension. Its help pages now describe a single unified extension, and the Companion listing tells users that its features have moved into the main extension.
If you still have both old extensions installed, remove them and install the current Tag Assistant extension from the Chrome Web Store.
How to use Google Tag Assistant: step by step
You do not need the extension for basic debugging, but installing it makes some cases work that otherwise fail.
1. Open Tag Assistant
Go to tagassistant.google.com and sign in with the Google account that has access to your Tag Manager or Analytics property.
2. Add your domain
Click Add domain and enter the full page URL, including https://. Turn on verbose logging if you want more detail in the browser console.
3. Connect
Click Connect. Your page opens in a new tab with a debug parameter (_dbg) added to the URL, and Tag Assistant starts recording.
4. Reproduce the journey
Click through the actions you want to test: view a product, submit a form, complete a test purchase.
5. Read the event list
Back in Tag Assistant, select each event on the left. Check Tags Fired, Tags Not Fired, Variables, and the Data Layer.
6. Confirm in GA4
Open DebugView in GA4 to see the same events arriving in the property.
7. Stop debugging
Click Stop Debugging or close the debug window. Your regular site is unaffected.
When you need the Tag Assistant Chrome extension
The extension shows the tags on the current page from the browser toolbar and adds a Troubleshoot tag button that opens a debug session. According to Google's help documentation, it is also needed to debug tags inside iframes, and it lets debugging continue into pop-ups and new tabs opened from the page.
If you use the extension, check that it has permission to read and change site data on the domain you are testing. Without that permission, it cannot see the tags.
What to look for in a Tag Assistant session
Most tracking problems show up as one of a handful of patterns. Work through them in this order.
Tag not found
No Google tag detected at all. The snippet is missing, blocked, or loads after Tag Assistant tried to connect.
Tag fires twice
The same GA4 or Ads tag is installed both in Tag Manager and in the page code. Duplicate events inflate conversions.
Tag does not fire
Open Tags Not Fired, select the tag, and check which trigger condition failed.
Wrong values
A purchase event fires but value or currency is empty. Inspect the data layer at that event to see what the site actually pushed.
Consent blocked
Tags wait for consent that never arrives. Check that your consent platform updates consent state for Google tags.
Wrong ID
A tag sends to an old or test measurement ID. Compare the ID in the event with the one in your GA4 property.
Tag Assistant cannot connect to my site
Google's help centre lists the usual causes. Check them before assuming the tag is broken.
Ad blockers
Pause ad blockers and privacy extensions on the domain you are testing.
The debug parameter breaks the page
Turn off Include debug signal in the URL in the connection settings.
Redirects
Several redirects in a row can stop the debug window loading. Connect to the final URL.
Late-loading tags
If the tag loads after a delay, click Retry.
Security policies
A content security policy, firewall, or proxy may block Tag Manager. Check the browser console for blocked requests.
AMP pages
AMP pages are not supported.
What Tag Assistant will not tell you
Tag Assistant confirms that a tag fired in your test session. It does not tell you whether the data is correct for every visitor, every browser, or every consent state. A tag can work perfectly in your Chrome window and still miss most Safari users or anyone who declined consent.
For that, compare platform numbers against your own back-end records, such as orders in your database versus purchases in GA4. A steady gap of a few percent is normal. A sudden jump or drop usually means a tag broke.
Google Tag Assistant FAQ
Is Google Tag Assistant free?
Yes. Both the web tool and the Chrome extension are free.
Does Tag Assistant work with server-side Tag Manager?
Server containers have their own preview mode in Tag Manager. Web-side events are still debugged in Tag Assistant.
Can other visitors see my debug session?
No. Debug mode applies only to the browser session you connected.
Does it work outside Chrome?
The web tool works in other browsers for many cases, but the extension and its extra debugging features are Chrome-only.
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