GA4, GTM, server-side and BigQuery consultant
Analytics you can trust. Ad campaigns that learn from real data.
I implement and fix GA4, Google Tag Manager, Meta Conversions API and Consent Mode v2 for online stores, B2B companies, mobile apps and the agencies that serve them. Your GA4 and ad platform numbers start matching your actual sales.
- 11+ years in analytics and online marketing
- 150+ companies I have delivered projects for
- Fixed price and deadline before we start
- Projects in English, Polish and German-speaking markets
Companies I have worked with
Sound familiar?
You spend more on ads every quarter, and your data tells you less
I hear one of these three problems most often. Each one can be verified on your accounts within a few days.
Campaigns lose efficiency and ROAS keeps dropping
Google Ads and Meta optimise for the conversions they can see. When some purchases and leads never reach them, or get counted twice, the algorithm learns from bad data and shows your ads to the wrong people.
How I fix it: server-side and Meta CAPI →100 orders in your store, barely 40 in GA4
Gaps in the dataLayer, sessions broken after the payment gateway redirect and mislabelled traffic sources mean you cannot tell which channel actually sells.
How I fix it: GA4 implementation →Half of your data vanished after the cookie banner went live
A banner that blocks scripts without Consent Mode v2 cuts you off from Google’s conversion modelling. Your numbers drop even though traffic stays the same.
How I fix it: Consent Mode v2 and CMP →Services
Pick your situation and I will show you where to start
I help three types of companies. Each has different data problems, so each starts somewhere else.
Every purchase counted once, in GA4 and in your ad platforms
Every lead attributed to its source and GDPR-compliant
The full user journey, from install to purchase
Running an agency?
I implement tracking for your clients white-label, under your brand. You keep the client relationship, I deliver the GA4, GTM, server-side or Consent Mode setup and documentation your team can hand over.
Talk to me about white-label work →Case studies
What changes once your data is in order
Three examples from 17 documented projects. Each one shows the problem, what I did and the result.
Fashion store on WooCommerce
The Pixel and Conversions API sent the same purchases without a shared identifier, so Meta was learning from duplicated data.
Blinkee: one analytics setup for many cities
App data did not match the ad platforms, and every market and channel had its own separate report.
Insurance calculator in a single-page app
Moving between steps produced no data, and contact requests landed in one bucket with no information about where they came from.
Honestly
Not everyone needs server-side tracking
Server-side tracking often does not pay off when more than 95% of visitors accept cookies, your customers rarely use ad blockers and you get little traffic from Safari and iOS. In that case it is cheaper and faster to fix what runs in the browser.
I check this on your GA4, Meta and consent banner data before I propose an implementation. If you do not need a service, I tell you so.
Before you move anything to the server
- Browser data has to be correct first. Server-side will not fix a broken dataLayer, it only forwards the same errors.
- Simple business: Stape Gateway plus Meta CAPI is usually enough.
- High traffic and large ad budgets: a full server-side GTM container.
How I work
You know the price and scope before we start
Every project follows the same 4 steps, whatever the service.
Free 30-minute consultation
You tell me what is not working. I look at your GA4, Meta or CMP data and tell you what you actually need.
Audit on your accounts
You add me as a user in GTM, GA4 and your ad accounts. I never need passwords, everything stays with you.
Plan and spec for your developers
You get the scope, a fixed price and a deadline in writing. Your developer gets a ready dataLayer specification.
Implementation, testing and sign-off
I test every event before publishing. I hand the project over when the numbers match your sales dashboard.
Pricing: implementations and audits have a fixed price agreed before we start. Consulting starts from €67 per hour excl. VAT in a 10-hour package, valid for 6 months. EU companies are invoiced with reverse-charge VAT. Details in services.
Free tools
Check your own data before you get in touch
Not ready to talk yet? These tools are free and work on your own accounts.
Free GA4 audit
An automated Data Studio report showing what works in your GA4 and what does not. A starting point, not a full diagnosis.
Run the audit →Server-side calculator
9 questions, 2 minutes, no email required. You get a recommendation with reasons and an estimated hosting cost.
Open the calculator →GTM template for B2B
A ready container to import. It measures contacts that skip the form in GA4 and Google Ads: a copied email address and a phone click.
Get the template →UTM link builder
Consistent campaign tagging, so GA4 attributes traffic to the right source.
Build a link →SHA-256 tester
Check that Google Ads and Meta receive a correct hash of the email and phone, not the hash of an empty field. Your data never leaves the browser.
Test a hash →
Who does the work
Marcin Miłowski, GA4, GTM and BigQuery consultant
I started out running B2B campaigns in Google Ads, Meta Ads and LinkedIn Ads. Today I focus only on analytics, because that is where budget decisions are made. I work on my own, so you talk directly to the person who implements.
I have implemented analytics for Inter Cars, run PPC and measurement for Vercom (EmailLabs, PushPushGo) and trained app analytics teams at companies such as Orange. I work alongside your developers or your agency, and I also deliver white-label projects for agencies.
FAQ
Questions I hear most often
How much does the first call cost?
Nothing. Every new client gets a free 30-minute consultation. After the call you know which service you need, what it costs and when I can start.
We already have GA4. Why would we need a consultant?
Installed GA4 is not the same as correct GA4. The most common problems are missing purchases, duplicated conversions, mislabelled traffic sources and data cut off by the cookie banner. The free GA4 audit shows whether this applies to your property.
Do we need server-side tracking?
Not always. If more than 95% of visitors accept cookies, your customers rarely use ad blockers and you get little Safari and iOS traffic, server-side often does not pay off. I check this on your GA4, Meta and CMP data during the free consultation.
Do you work with our developers or agency?
Yes. I prepare the dataLayer specification and instructions for developers, and I deliver white-label implementations for agencies.
Do our data and accounts stay with us?
Yes. I work in your GA4, GTM and ad accounts as an added user. I never need passwords.
Do you work with companies outside Poland?
Yes. I work remotely with companies in English-speaking markets and Germany. Meetings run in English or Polish, and the booking calendar shows slots in your own time zone.
How do you invoice?
In euros, excluding VAT. Companies in the EU with a valid VAT number are invoiced under the reverse-charge mechanism.
Let’s find out how much bad data is costing you
30 minutes, free and with no obligation. After the call you know what to fix first and what it will cost.