container audit

GTM-NB3RKGC9

110 tags, 1 custom scripts, 2 third-party hosts — an ordinary container, near the middle of what we measure (median: 39 tags, 4 custom scripts).

1 custom HTML tag carrying 33 KB of JavaScript. This runs on every page the container loads on.
2 third-party hosts reachable from its tags.

Tags110

Custom scripts1

Third parties2

Delivered674 KB

Versions53

What we observed

A real browser loaded jet2holidays.com a month ago and recorded every request it made. This is what happened, as distinct from what the container is configured to do. It is one page load — anything that fires only deeper in the site did not fire here.

Container loaded from googletagmanager.com — Google

Measurement sent to google-analytics.com — Google

Consent OneTrust answered its own API. Measurement fired beforehand but carried no identifier — analytics_storage was denied, which is Consent Mode working as designed rather than a gap. 10 hosts appeared only after consent was granted. Google recorded gcs=G100 (all denied).

Third parties contacted 25 hosts — cdn-ukwest.onetrust.com, maxcdn.bootstrapcdn.com, fonts.googleapis.com, alcdn.msauth.net, media.jet2.com, s.go-mpulse.net, assets.adobedtm.com, api.feefo.com, and 17 more

dataLayer events seen gtm.js, gtm.dom, OneTrustLoaded, OptanonLoaded, gtm.load, experience_impression, optimizely_decision, myJet2banner

Where the data goes

Not observed — on the page we loaded, measurement went to Google and nowhere else. observed on jet2holidays.com More info »

Findings

Ordered by consequence. review has a concrete cost when it bites; info is real but depends on your setup. Seen is how common it is across the containers we have measured — reported separately on purpose, because common and harmless are different claims.

reviewdocument.write (1)

1 piece of custom code call document.write.

Whydocument.write blocks the HTML parser while it runs, and browsers ignore it entirely once the page has finished parsing — so an async-loaded tag using it can silently do nothing.

CheckIf these tags fire on page load they are costing render time; if they fire later they may not be working at all. Worth confirming the tag still does what it was added to do.

Seenseen in 18.4% of 46,522 containers measured

infoOne variable that a great deal depends on (108)

"currencyCode" is read by 108 tags and triggers — more than anything else in this container.

WhyGTM shows you where a variable is defined, never how much depends on it. Editing this one touches a large share of the container at once, and whatever breaks will surface somewhere that looks unrelated to the change.

CheckBefore changing it, check what reads it. If it feeds both measurement and consent or routing logic, split those uses apart first.

Seenseen in 10.1% of 46,522 containers measured

infoConsent configuration detected (1)

The container declares one or more consent signals.

WhyConsent handling is present in the container. This describes what the artifact declares; what actually happened on the page is measured separately, above.

CheckConfirm these settings match the consent policy you intend to enforce, and compare them with the before-and-after observation.

Seenseen in 44.6% of 46,522 containers measured

Third parties it can reach

Each host is a party that can execute code or receive data in a visitor's browser. Follow one to see who else loads it. More info »

www.google-analytics.com ×109wa.me ×1

Detected on

Sites observed loading this container. A container used across many hosts is a shared template; one on a single host is a bespoke build. Follow a site to see every container it loads.

jet2holidays.com

What this audit describes

Containers change. These findings describe one specific artifact, and you can re-fetch it to check this reading.

Container	`GTM-NB3RKGC9`
Published version	`53` — the identity of this configuration. It changes only when someone publishes.
Read at	2026-08-20 22:17:17 UTC (a month ago)
Source	`https://www.googletagmanager.com/gtm.js?id=GTM-NB3RKGC9`
Body checksum	`c0a771e908cb0e985024be9779e0e004e23640940297516e373a32428d59cebb` Evidence of the exact bytes we read, not an identity: Google varies the response per request, so re-fetching an unchanged container yields a different checksum. Compare the published version instead.

Re-audit

This reading is from a month ago. A container can be republished at any time, and nothing here updates on its own — a fresh read is the only way to know whether it still says this. Running it again replaces this page in place, so the link keeps working.

Re-audit GTM-NB3RKGC9

Check another container

Put this container under version control. Tagora exports it to a repository you own, so every change arrives as a pull request. How it works »