Checking a tag installation without paid tools
Auditing a tracking install end to end doesn’t require a paid monitoring subscription. Four free tools cover the vast majority of cases: Google Tag Manager’s preview mode, the Tag Assistant extension, the Meta Pixel Helper extension, and the browser developer tools’ Network tab.
The situations I handle
- Need to check a tracking install after going live, with no budget for a tool
- Doubt over whether tags still fire correctly after a theme or module change
- No way to tell if GTM, GA4 or the Meta pixel are actually active
- A provider claims tracking is in place but nothing is easily verifiable
- Wanting to audit an install yourself before paying for an external audit
- A check to repeat regularly after every major site update
A full audit with only free tools
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1. Confirm the GTM container is present (Network tab)
Dev tools (F12), Network tab, reload the page, filter on gtm.js. A 200 request with the expected ID (GTM-XXXXXXX): the container loads. Nothing: the tag isn’t installed on that page, before configuration even comes into it.
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2. Launch Google Tag Manager’s preview mode
From GTM, click Preview, enter the site’s URL: a debug session opens in a new tab with a ’Tag Assistant Connected’ banner. I browse normally: every page lists its fired tags (Tags Fired) and unfired ones (Tags Not Fired).
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3. Check every checkout event one by one
I walk a full journey: product page, cart, checkout start, payment, confirmation. At each step I click the event (view_item, add_to_cart, begin_checkout, purchase) and open Variables to check value, currency, items, transaction_id.
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4. Install and use Tag Assistant outside GTM
For a gtag.js tag placed directly without GTM, or a quick check, the Tag Assistant extension lists Google tags detected on the page and flags common configuration errors.
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5. Install and use Meta Pixel Helper
The extension shows an icon with a badge as soon as a Meta pixel is detected. I click it to see events sent (PageView, ViewContent, AddToCart, Purchase) and warnings, such as a missing value parameter.
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6. Confirm every real send in the Network tab
On top of the extensions, I filter Network on collect (Google) and tr (Meta) during each action. Seeing the request leave at the right moment, to the right domain, is the most direct proof an event was sent.
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7. Repeat the test in private browsing, consent declined
Private window, decline consent on the banner, replay the journey. Analytics and advertising tags should stay silent in preview mode or Network: otherwise, it’s a consent configuration issue, distinct from a tracking problem.
What these tools don’t replace
These four tools cover most of a one-off audit, with limits worth knowing:
- They check the moment of the test, not continuously: a paid monitoring tool alerts automatically if a tag breaks later.
- They show what fires on the browser side, not a server-side send like Meta’s Conversions API, which leaves the server directly.
- A tag that fires correctly in testing can still fail for a real visitor due to an ad blocker: the audit confirms the install, not that 100% of visitors will be measured.
Go further
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Installing Google Tag Manager on PrestaShop
Setting up the container and dataLayer correctly from the start.
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Ecommerce events that matter
The list of recommended GA4 events and their parameters.
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My conversions aren’t showing up
The ordered method when a specific event is missing.
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Duplicates in the statistics
Using the same tools to spot a tag installed twice.
Describe your need in one minute
A few targeted questions so I can reply with an estimate rather than another questionnaire.