The challenge

A digital bank had built its entire tag management stack on Google Tag Manager over three years — 47 tags covering Adobe Analytics, Google Ads conversion tracking, Hotjar, and several third-party marketing pixels. The decision to adopt Adobe Experience Platform required migrating to Adobe Launch as the tag management layer. The complication: a regulated financial institution with change management requirements, no deployment windows during business hours, and a risk-averse engineering team with limited availability for analytics projects.

Tag inventory and dependency mapping

Every GTM tag, trigger, and variable was documented in a migration specification before any Launch configuration began. Tags were categorised by business criticality — analytics and conversion tracking at the top, marketing pixels below — and dependencies between tags were mapped explicitly.

The inventory revealed three GTM tags firing on triggers that had never been properly validated — they appeared to be firing on every page regardless of their intended conditions. These were flagged as defects to fix during migration rather than replicate in Launch.

Parallel environment strategy

Rather than a big-bang cutover, we built the Adobe Launch implementation in parallel with GTM still running. Using a feature flag in the bank's deployment system, we enabled Launch on a 10% traffic split first — allowing us to validate Launch tag firing against GTM on live production traffic without risk.

The parallel period ran for three weeks. During this time, we compared Adobe Analytics data collected through GTM's Universal Analytics tag against data collected through Launch — identifying and resolving a timing issue where Launch was firing before the data layer was fully populated on certain page types.

Cutover and GTM decommission

Cutover was executed during a planned low-traffic window with engineering support on standby. The GTM snippet was removed and Launch promoted to 100% traffic in a single deployment. Real-time monitoring of Adobe Analytics data confirmed consistent collection within the first 30 minutes.

GTM was kept in read-only mode for 30 days post-cutover before full decommission — allowing rollback capability without redeployment if any issues were discovered in the first month.

Outcome

The migration completed in eight weeks with zero incidents during cutover. Three previously undetected tag defects were fixed in the process. The bank's digital team now operates on a single tag management system aligned with their Adobe Experience Cloud investment, with a cleaner, more maintainable implementation than the GTM setup it replaced.