Google Tag Manager (GTM)
What is Google Tag Manager (GTM)?
Google Tag Manager is a free container that sits on a site and holds its tracking code — GA4, the Meta Pixel, conversion tags — so tags are added and changed there, not in the site’s code. Each change is a version you preview, publish and roll back if it breaks. The container also decides which tag fires, on which page, and after which action.
Example
A shop wants three things at once: orders counted in Google Ads, the same signal sent to Meta, and a heatmap on two pages. Without a container that is three developer tickets, three releases and three waits.
With a container the code goes on once. The marketer adds the tag, opens preview mode and watches live whether it fires on the thank-you page only, rather than on every load. Version 12 is published. A week later the page feels heavy, version 11 is restored in one click, and the site is back where it was — no night release, no developer.
The convenience has a real price. Every tag is third-party JavaScript running in the visitor’s browser. Six tags in the container mean six external files on every load, which is how containers end up weighing more than the site they were added to.
Why it matters for a business
A container gives marketing speed, and it gives away rights. Whoever can publish in it can ship code that runs on every page, the payment page included. So two things belong in writing at the start: whose name the account is in, and who may publish. A contractor who leaves with publishing rights keeps access to your site without ever having had access to your server.
Who owns the advertising accounts and the data is the neighbouring question, and it is answered on the digital marketing page. The rule here is the same one: the account is yours, access is granted and can be withdrawn.
What to ask
- Whose name is the Tag Manager account in, and who is allowed to publish a version?
- Which tags are in the container right now, who added them, and what is each one for?
- Is consent wired into the container, so a refusal actually stops the marketing tags?
- When was an unused tag last removed, and who watches how much the tags weigh?
- Is there a version to roll back to when something breaks on a Friday evening?