+21% Meta bids and +28% Google sign-ups with Server-side Tracking

The overview

OnlineVeilingmeester, a leading Dutch online auction house, set out to improve tracking accuracy and data reliability amid tightening privacy regulations and a fragmented measurement landscape. Alexander Oostindiën, Freelance & Interim Digital Marketing Specialist for OnlineVeilingmeester, partnered with TAGGRS to strengthen the measurement setup using Server-side Tracking, GA4, GTM, and advanced tagging.

In this case study, you'll discover how Alexander and TAGGRS future-proofed OnlineVeilingmeester’s data collection, optimized campaigns, and ensured privacy compliance.

The challenges

1. Gaps in conversion tracking across the customer journey

OnlineVeilingmeester’s tracking setup was dispersed across Google Tag Manager, hardcoded scripts, and backend logic. This fragmentation made it difficult to capture a unified and trustworthy view of user actions from first click to conversion. As a result, conversion measurement was often inconsistent and key touchpoints were missed.

2. Lack of centralized data management and alignment

With no single source of truth for data collection and event management, the marketing team struggled to align efforts with development and privacy requirements. This lack of centralization hindered campaign optimization, reliable attribution, and data-driven decision-making.

3. Data loss due to privacy and technical barriers

Strict privacy laws, like GDPR, and browser technologies that block cookies and tracking scripts led to significant data loss. The custom-built React environment further complicated the implementation of standard tracking solutions, making reliable data collection even more challenging.

TAGGRS approach

1

Analysis and audit

It all began with a full audit of OnlineVeilingmeester’s measurement setup, mapping data flows and identifying loss points caused by technical complexity and privacy barriers.

2

Strategic solution design

We developed a tailored Server-side Tracking strategy which included migrating all tracking to Google Tag Manager for centralized management, implementing TAGGRS’ sGTM tagging hosting, and enhancing event enrichment. «Our goal with server-side tracking was to improve the quality and reliability of our data. We wanted to measure conversions without relying on client-side scripts that get blocked by browsers or ad blockers,» said Alexander Oostindiën.

3

Implementation

The rollout involved close collaboration between marketing, development, and TAGGRS leading to:
• Migration of hardcoded scripts to GTM
• Integration of Server-side Tracking for key conversions (sign-ups, bids)
• Ensured compliance with privacy regulations and consent management.

4

Support and collaboration

TAGGRS provided responsive support throughout, «quick to act, direct communication, and solution-oriented thinking».

«TAGGRS has been a pleasant team to work with and, not unimportantly, delivered results: Meta +20.7% measured bids via the Conversion API and 28% more measured sign-ups in Google Ads.»
- Alexander Oostindiën, Performance Marketer

The results

2%

Meta bids measured via Conversions API

0%

More measured Google sign-ups

70%

reliable cross-channel conversion data for smarter budget allocation

Looking ahead: smarter decisions, stronger growth

With a new tracking stack in place, OnlineVeilingmeester can now rely on accurate data to optimize campaigns, refine the customer journey, and confidently invest in future growth. Alexander recommends server-side tracking as the foundation for any organization seeking reliable attribution and future-ready marketing.

About OnlineVeilingmeester

OnlineVeilingmeester.nl is a prominent online auction house, facilitating the buying and selling of a wide range of goods for both businesses and consumers. The company’s success relies on a seamless digital experience and accurate measurement of the entire customer journey. From first click to successful bid or sale.