container audit

GTM-NVL3G4N

This container ships 197 hand-written scripts (89 KB of JavaScript) to every visitor — more than 99% of the 46,522 containers we have measured. That is an application's worth of code, delivered as tag configuration.

478 published versions — each one live for every visitor the moment it was published.
duplicate-ads-conversion is uncommon — under 4% of the containers we have measured have it. That is context rather than a verdict: a server container is rarer still and is a sign of a mature setup. What it means is in the finding itself.

Tags340

Custom scripts197

Third parties24

Delivered744 KB

Versions478

What we observed

A real browser loaded onet.co.jp 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 no consent gate responded on this page, so there was nothing to hold measurement back (banners are often shown only to visitors in certain regions, and this was not a European visit). 2 hosts appeared only after consent was granted. Google recorded gcs=G1 (no consent signal).

Third parties contacted 25 hosts — cdnjs.cloudflare.com, fonts.googleapis.com, www.googletagmanager.com, www.clarity.ms, scripts.clarity.ms, www.google.com, ad.doubleclick.net, static.ads-twitter.com, and 17 more

dataLayer events seen gtm.js, gtm.dom, gtm.load, gtm.scrollDepth

Where the data goes

Not observed — on the page we loaded, measurement went to Google and nowhere else. observed on onet.co.jp 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.

reviewHardcoded http:// URL (14)

14 pieces of custom code reference a plain http:// address.

WhyOn an https:// page the browser blocks or upgrades these. Blocked means the tag quietly stops working; upgraded only works if that host also serves https.

CheckCheck whether the hosts below still respond over https, and update the URLs.

Seenseen in 12.8% of 46,522 containers measured

reviewdocument.write (9)

9 pieces 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

reviewWrites cookies directly (4)

4 pieces of custom code set cookies in code.

WhyCookies set this way bypass GTM's consent settings, because the consent checks live in the tag templates rather than in raw JavaScript.

CheckIf any of these cookies are used for analytics or advertising, confirm they are still gated on a consent decision.

Seenseen in 21.2% of 46,522 containers measured

reviewSame Google Ads conversion defined more than once (1)

1 conversion action is defined by more than one tag.

WhyA conversion ID plus label identifies one action. Two tags carrying the same pair can report the same conversion twice, inflating conversion counts and the ROAS that bidding runs on.

CheckCheck whether both tags can fire on the same page. If they can, your Ads reporting is overstating this action and automated bidding is optimising against it.

Seenseen in 3.8% of 46,522 containers measured

infoLoads JavaScript from another host (60)

60 pieces of custom code fetch and run JavaScript from another host.

WhyWhatever that host serves executes with full access to the page — it can read the DOM, cookies and form fields. The code is not in this container, so it can change at any time without any change here.

CheckConfirm you recognise every host below and that someone owns the relationship. A host you cannot name is the one to chase.

Seenseen in 54.4% of 46,522 containers measured

infoUses browser storage (21)

21 pieces of custom code read or write localStorage or sessionStorage.

WhyBrowser storage persists across visits and is not covered by cookie consent tooling, so it is easy to overlook when auditing what you keep on a visitor's device.

CheckConfirm nothing personal is being kept there, and that it is covered by your privacy notice.

Seenseen in 23.3% of 46,522 containers measured

infoVendor IDs written into custom code (10)

10 vendor IDs are pasted directly into custom HTML rather than held in a variable or template.

WhyChanging a property, pixel or account then means editing every tag that mentions it, and any one that gets missed keeps sending to the old destination indefinitely.

CheckFine if the ID never changes. If you have ever migrated a property, check that none of these still point at the old one.

Seenseen in 31.4% 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 »

What the custom templates can do

Custom templates are third-party code shipped inside the container. Injecting scripts and running page globals is ordinary for them — most tag templates need it to work — so this is an inventory, not a warning. It lists the capability each template declares so you can match it against templates you meant to install.

__cvt_5DFVR gallery injects code from s.yimg.jp · runs page-level globals

__cvt_7276333_808 private injects code from static.ads-twitter.com · runs page-level globals

__cvt_7276333_809 private injects code from static.ads-twitter.com · runs page-level globals

__cvt_7276333_923 private runs page-level globals

__cvt_KVFNC gallery injects code from s.yimg.jp · runs page-level globals

__cvt_PBK7R gallery injects code from s.yimg.jp · runs page-level globals

__cvt_TBNCF gallery injects code from s.yimg.jp · runs page-level globals

__cvt_WBTFX gallery injects code from s.yimg.jp · runs page-level globals

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.

onet.co.jp

What this audit describes

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

Container	`GTM-NVL3G4N`
Published version	`478` — the identity of this configuration. It changes only when someone publishes.
Read at	2026-08-12 22:40:13 UTC (a month ago)
Source	`https://www.googletagmanager.com/gtm.js?id=GTM-NVL3G4N`
Body checksum	`b6478a48e01b4876f6595b47246734dc146d2d7f86f358ba68a6f6237bf15fa1` 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-NVL3G4N

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