How Hey Marketing scaled Server-side Tracking from three clients to fifty by showing real business impact
The overview
Hey Marketing is a performance marketing agency based in Eindhoven. Founded around five and a half years ago, the team of roughly 13 people covers the full breadth of online marketing, from SEA and SEO to GEO, social ads, and email marketing. Their clients are mostly SME businesses in e-commerce, lead generation, and B2B, including many local companies around Eindhoven along with a handful of national and international accounts.
Data and tracking sits with the SEA team, led by Rens van den Heuvel. Rens has been at Hey Marketing for over three years, starting in paid search across Google Ads and Microsoft Ads before increasingly specializing in data and tracking. That shift is what brought him into close contact with TAGGRS.
Hey Marketing was one of TAGGRS's earliest partners, joining in early 2024, and now has more than 50 clients live on the platform.
- Rens van den Heuvel, SEA Lead at Hey Marketing
The challenge
Two things prompted Hey Marketing to start looking for a permanent data and tracking partner.
The first was Google Consent Mode V2. When news of it broke in late 2023, the agency knew clients would soon need a cookie banner for consent, and that a live banner would cut into the data they could measure. For some clients, the impact would be significant, and Hey Marketing wanted to be prepared.
The second was a longer-standing problem. A structural gap sat between the data in GA4 and what actually reached the systems behind clients' websites and online stores, and Hey Marketing wanted to close it. When the underlying data is off, no amount of campaign work or ad spend will produce the right result.
The solution
Instead of switching all their clients to Server-side Tracking at once, Hey Marketing began with three. All of them were larger accounts where the gap between GA4 and transaction data showed up most clearly, and where the new cookie banner was likely to do the most damage. That made them strong test cases for the wider rollout.
The harder part was getting clients on board. Server-side Tracking can come across as a sales pitch or just another tool to pay for. So instead of pitching the technology, Hey Marketing put the gap in front of each client and made a simple case. Closing it means more conversions are measured accurately, and the ad platforms optimize on the signals they receive, so a more complete and accurate signal leads to better campaign performance. They framed Server-side Tracking as an investment in results rather than a technical cost, and ran it as a test first, leaving the decision to continue until afterwards. All three are still running Server-side Tracking with TAGGRS today.
Across the first three clients, Hey Marketing saw a data uplift of at least 20%, along with a measurably closer match to actual sales data. That was enough to move the rest of their clients onto TAGGRS, and the transition happened quickly. Rens credits responsive support during setup for much of that pace. As a paid search specialist building up his data knowledge, having that support to lean on made a real difference.
The results
Rens walked through the cases of the three clients that Hey Marketing first onboarded onto TAGGRS.
Schuttingkampioen delivers and installs high-end wooden and composite fencing, and has worked with Hey Marketing for about two years. For a lead generation business, not every lead is worth the same. A low cost-per-lead means little if those leads rarely turn into paying customers.
Server-side Tracking became the foundation for feeding real customer status back into Google Ads and Meta Ads through offline conversion imports via Zapier, while Enhanced Conversions improved ID matching. That allowed for the campaigns to be evaluated based on actual customers rather than quote requests.
The insight that surfaced was telling. Some campaigns produced a strong cost-per-lead and plenty of requests, yet few quality customers. Acting on it, the agency shifted spend toward Search and away from Performance Max, and toward regional campaigns in Noord-Brabant and Limburg over national ones. Regional clicks cost more, but people prefer a fencing company based nearby. The trade-off was deliberate. The cost per quote request rose, but the cost per customer who actually converted came down, which is what the client cares about.
Mr. Sushi is a nationwide sushi chain with more than 60 locations in the Netherlands, and a client for several years. It is a high-volume account, so even small measurement gaps translate into a lot of missed or misattributed data.
Filtering the TAGGRS dashboard on the purchase event, Hey Marketing found that Enhanced Conversions effectively weren't being sent, with 0% of the data coming through. That prompted a conversation with the team behind Mr. Sushi's ordering portal, and the privacy policy and cookie banner were updated so that hashed email addresses and phone numbers could be sent with each purchase event, in line with GDPR.
Enhanced Conversions then went from 0 to 100% measured correctly on purchase events, with a matching growth in ROAS. Because it is such a high-volume account, the uplift in data is proportionally large.
Hevu Tools is an online building-supplies retailer with a physical location in Beek en Donk, and a client of more than three years. Early on, campaigns delivered exceptional returns, with a ROAS as high as 1800% driven by sharp pricing. Any data instability threatened a proven, profitable setup. Once a cookie banner went live to meet Consent Mode V2, data quality collapsed, with roughly 30% of data lost, and there was no stable base to work from.
In early 2024, Hey Marketing set up Server-side Tracking and cleaned up the web container. That restored clean data, which let the bidding strategies read the right signals and optimize properly. ROAS now sits lower than the old 1800%, which is expected once a cookie banner is added where there was none. However, over the following two years, online revenue grew by roughly 90%, on a stable foundation the agency could keep scaling on.
These cases reflect how Hey Marketing now works by default. It runs server-side tracking mainly across Google Ads and Meta Ads, alongside GA4, feeding offline conversion data back through Zapier to match leads to customers. Once a client spends meaningfully on those platforms, roughly €1,000 a month or more, the gain in results outweighs the setup cost, so the agency treats it as the standard approach. It remains optional only on very small budgets.
Key takeaways for agencies
Show the gap, not the tool. Hey Marketing showed the value of Server-side Tracking to clients by presenting the concrete gap between their GA4 and transaction data, then frame the fix as an investment in results. Learn more about how to present Server-side Tracking to your clients for real business impact.
Weigh the cost of not switching to Server-side Tracking. Agencies tend to anchor on what Server-side Tracking costs to set up. The more useful comparison is against the results a client misses out on without it, which is where the real cost sits. That framing is what convinced Hey Marketing's first clients, and it holds for any agency still weighing the decision.
Cleaner data changes the conversation and the KPIs. Moving from ROAS to POAS, or from cost-per-lead to cost-per-customer, changes numbers a client has watched for years. Lower ad-platform performance can sit alongside real growth. Explaining that shift and earning the trust to make it is part of the job, and it may take months of difficult conversations.
Don't overlook consent compliance. When you are busy adding and removing things in the tracking setup, it is easy to forget to reflect those changes in the privacy policy and cookie banner. Sending hashed data without the right consent breaks GDPR compliance, and, especially for a larger brand, comes with a reputational risk.
The role is shifting toward strategy. As AI takes over routine execution and analysis, the value of an SEA specialist moves toward strategic advice, thinking alongside the client almost as a business partner. Rens sees this as something to embrace rather than fear. The one thing the team keeps reminding itself is to keep thinking for yourself.