Guide · Tag Assistant
Google Tag Assistant: how to check your tags, and what it cannot tell you
Tag Assistant tells you whether a tag fired, with what data and under which consent. It does not tell you whether GA4 counted the visit or the ad platform kept the conversion. Most tracking arguments happen in that gap.
Short answer: open tagassistant.google.com, click Add domain, enter your site’s URL with https and click Connect. Your site opens in a debug window, and Tag Assistant lists every tag, event, data layer push and consent state as you browse. Install the Tag Assistant Chrome extension too: without it, tags inside iframes and new tabs stay invisible.
How do you connect Google Tag Assistant to a site?
- Go to tagassistant.google.com and click Add domain.
- Enter the full URL of a page that should carry the Google tag, starting with https:// or http://, and click Connect.
- Browse the site in the window that opens. Tag Assistant keeps listening while you stay on the same domain and the page carries the Google tag. Regular visitors see nothing of this.
- Stop with Stop Debugging, or close the debug window.
On connection Tag Assistant adds a _dbg parameter to the URL. That parameter is what makes your events show up in GA4’s DebugView at the same time. If the parameter breaks something on the page, edit the domain and untick Include debug signal in the URL.
The Chrome extension is worth installing first. Google lists four things that only work with it: Google tags inside an iframe, pop-ups and new tabs opened from the page, the debug window as a normal tab instead of a pop-up, and several windows in one debug session. The old Tag Assistant Legacy and Tag Assistant Companion extensions are now one extension, and Companion is on its way out.
Source: Tag Assistant Help, Troubleshoot with Tag Assistant, read on 6 October 2026.
Or see what your team should look at first: the Paid Media Capacity Check, being built nowWhat should you look at once it is connected?
| Where | What it answers | The mistake to avoid |
|---|---|---|
| The event list on the left | What happened on each page, in order: page load, clicks, data layer pushes. | Reading the first page only. Click through to the page where the conversion happens. |
| Tags, per event | Which tags fired and which did not on that event. | Assuming “fired” means “received”. It means the browser sent something. |
| The tag’s Output | The hits the tag sent, with their parameters. | Skipping it. The hit is where an event name or a value turns out to be wrong. |
| Data layer | What your site pushed, and when. | Stopping here. An event in the data layer has not gone anywhere yet. |
| Consent tab | The default consent state and the update after the banner, in the On-page Default and On-page Update columns. | Testing only with “accept”. Run it again and reject. |
Google’s consent guide is specific about the order: the default consent state has to be set before any tag fires. An empty Consent tab means consent mode is not set on that page, or the Google tag never loaded. Source: Google Tag Platform, Troubleshoot consent mode with Tag Assistant, read on 6 October 2026.
Three things Tag Assistant showed me that looked like bugs
“No Google tag found” on a site that measures fine
Our own site loads Google Tag Manager only after a visitor accepts cookies. Before that, the page loads no third-party code at all. Connect Tag Assistant without accepting and it finds nothing, because there is nothing to find yet. Accept in the debug window, reload, and the tags appear. On a consent-first site, an empty Tag Assistant is the banner working, not tracking broken.
The lead was in the data layer, and GA4 never got it
On two sites we built in September 2026, the click on the email address pushed a generate_lead event to the data layer, and Tag Assistant showed it there every time. GA4 still received only page views and engagement. The container held the Google tag and nothing else, and that tag did not forward events the page sent itself. The fix was a GA4 event tag in the container, listening to a custom data layer event. Tag Assistant had the answer the whole time: the event sat in the data layer and no GA4 hit carried it.
The tag fired, and GA4 showed a fraction of the visits
On one client account, a paid campaign reported 120 clicks and GA4 showed 4 sessions. The tags fired on every visit. Each GA4 hit carried gcs=G100, which means analytics and ad storage were both denied. Google does not count a hit with analytics storage denied as a user or a session in its reports, and a small site never reaches the volume where modelling fills the gap. 4 of 120 was not a bounce rate. It was the share of people who accepted cookies.
What can Tag Assistant not tell you?
- Whether GA4 reports the visit. Tag Assistant sees the hit leave the browser. Consent, filters and thresholds decide what reaches the reports. Check DebugView, then the reports a day later.
- Whether the ad platform kept the conversion. A conversion tag that fires can still be rejected or attributed elsewhere. The platform’s own conversion diagnostics answer that, not the browser.
- What your visitors see. Your debug session runs in your browser, with your consent choice and without the ad blocker many visitors have. Tag Assistant is a test of the setup, not a sample of the traffic.
Two limits come straight from Google’s help page: Tag Assistant does not support AMP pages, and repeated redirects can stop the debug window from loading.
Why will Tag Assistant not connect?
Google’s help page lists the usual causes. In the order I would check them:
- The page has no Google tag yet. On a consent-first site, accept cookies first. Otherwise try a URL where the tag should be.
- An ad blocker stopped the tag. Turn it off for the pages you test.
- The tag loads after Tag Assistant tried to connect. Click Retry.
- The
_dbgparameter breaks the page. Untick Include debug signal in the URL. - The tag lives in an iframe. That only works with the Chrome extension installed.
Questions people actually ask
How do I use Google Tag Assistant?
Go to tagassistant.google.com, click Add domain, enter your page URL with https and click Connect. Browse your site in the debug window and read the events, the tags that fired, their output and the Consent tab. Stop with Stop Debugging.
Why does Tag Assistant say no Google tag was found?
Either the page has no Google tag, an ad blocker stopped it, or the tag loads only after consent. On a site that loads Google Tag Manager after the cookie banner, accept cookies in the debug window and reload.
Do I still need Tag Assistant Companion?
No. Google combined Tag Assistant Legacy and Tag Assistant Companion into one Tag Assistant Chrome extension, and Companion is being deprecated. Install the current extension to debug iframes, pop-ups and new tabs.
How do I check consent mode with Tag Assistant?
Open the tag’s Output and the Consent tab. The On-page Default column shows the state before the banner, and the On-page Update column shows the change after the visitor chooses. Test once accepting and once rejecting.
If Tag Assistant shows my GA4 tag firing, why is GA4 missing data?
Because firing is not counting. A hit sent with analytics storage denied reaches GA4 but is not reported as a user or session. Check the gcs value of the hit: G100 means analytics and ad storage were denied, G111 means both were granted.
Related reading
- Google Tag Manager MCP. Reading containers, tags and triggers from an AI assistant.
- Google Analytics MCP. The GA4 side: what an assistant can read once the data arrives.
- Reading Google and Meta together. Why the platforms and GA4 never agree, and what to compare instead.
- Google Tag Assistant en español. This guide, written for people searching in Spanish.
Last updated:
Who wrote this
I’m Manu. I’m a media buyer, and I built Climent Ads Assistant because no ads software I paid for was worth it. It reads Meta, Google Ads, GA4 and Search Console one client at a time, and compares what the ad platform reports with what GA4 sees.