Freelance Growth Hacker EN

Freelance Growth Hacker EN

Spaans / Engels / Nederlands

I’m Bart Stemkens, a freelance growth hacker. I help SaaS and app-based companies grow through data, experimentation, and smart use of marketing channels. Whether it’s driving more traffic, improving activation, or boosting retention, I support teams with strategy and run full-funnel experiments from start to finish. I bring over 11 years of experience with startups like Squla, StudyGo, KIMO, and Valyuu, as well as corporates like Nationale Nederlanden and Nescafé.

You can hire me starting from 1 day per week for:

  • Developing and executing your marketing strategy or growth roadmap
  • Setting up or optimising a specific channel (such as SEO, SEA, display, or affiliate)
  • Temporary support as a growth or performance marketer
  • Coordinating external agencies and freelancers

Prefer a one-off analysis first? Try the “Just-tell-me-what’s-wrong” Growth Audit ($999): a sharp, compact assessment with clear insights and actionable ideas.

👉 Book a free video call or call me directly at +31 6 833 29 344.

What is growth hacking?

Growth hacking isn’t a trick, it’s a way of working. It means running structured experiments across the entire funnel, from attracting new users to activating and retaining them.

At the core is a living backlog of ideas—things you want to test, each mapped to a specific stage in the AARRR funnel (Awareness, Acquisition, Activation, Retention, Referral). Every idea gets a KPI and is ranked based on impact, confidence, and ease. From there, you build a roadmap and run experiments one by one.

The goal? Less guesswork, more learning what actually works. No endless debates, just a steady rhythm of testing, learning, and moving forward. Growth hacking is a process, and if you do it right, it keeps you improving the things that truly move the needle.

My specialities

Growth strategy & roadmap

Tell me your ambitions and I’ll map out the growth opportunities, plus the order in which to tackle them.

SEO & GEO

More visibility without ad spend, across search engines and emerging AI engines.

CRO & activation

Build hypotheses, run tests and lift both activation rates and conversions.

Performance marketing

Profitable online advertising on Google, LinkedIn, Meta and more, from strategy through full technical setup.

Marketing automation

Lead scoring, nurture flows and automated follow-ups that keep you top of mind.

Tracking & data analytics

I connect the tools and set up a weekly reporting dashboard, so progress is crystal-clear every Monday.

Highlighted results

These are some of the outcomes I achieved in recent projects, results I can deliver for you as well.

  • Studira grew from zero to 5,000 paying users in 14 months with a 90% trial-to-paid conversion thanks to the acquisition strategy I designed. Read the case.
  • KIMO reached 150,000 app users in 10 countries after we rolled out my acquisition plan. Read the case.
  • Bieden & Wonen scaled its franchise network from 3 to 10 locations in two years through the growth strategy I built. Read the case.
  • Chirpley onboarded 20,000 influencers in its first year with the GTM strategy I created. Read the case..

But numbers only tell half the story. This is how clients describe working with me:

“Bart is a multi-skilled professional able to make your business grow. He can handle high levels of complexity, and is pleasant to work with at all times.”

— Rens, CEO @ KIMO
“With Bart, you have everything you need to grow and scale—no extra resources required. If you could clone him, you’d leave your competitors in the dust.”

— Sarah, Head of Growth @ Small Improvements
“Smart, pragmatic, hard-working, and a great guy to have around. Our intake doubled, and costs were cut in half. Bart takes initiative, makes decisions, and gets things done.”

— Marnix, Proposition Manager @ Nationale-Nederlanden

View all testimonials

Clients

The companies below give an idea of who I work with. I am not tied to any one sector, but lately I have focused on SaaS and app companies in EdTech, social media, HR tech and FinTech, serving both B2B and B2C markets.

  • Squla
  • Nationale Nederlanden
  • Nescafé
  • StudyGo
  • Bieden & Wonen
  • Klup
  • Legal Fit
  • Biedboek
  • Financieel Gezond
  • Chirpley
  • Zoegas
  • Valyuu
  • Small Improvements
  • Nestlé
  • Innoleaps
  • Closure
  • Stekkies
  • KIMO
  • DFNS
  • RFM
  • 4S Real Estate

FAQ

‣
Do you handle everything yourself or do you outsource?

With more than ten years in growth marketing I’ve learned new tactics again and again—from UX tests and CRO experiments to building dashboards, running Google Search campaigns and setting up CRM flows. That makes me fairly all-round. When a true specialist can move faster, I bring someone from my network on board, always in consultation.

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Do you also take care of strategy?

Yes. We start with a short session to define goals, KPIs and market position. A concise roadmap follows—no 60-slide deck—that we begin executing right away and adjust based on the data.

‣
Do you work on-site?

Yes. We start with a short session to define goals, KPIs and market position. A concise roadmap follows—no 60-slide deck—that we begin executing right away and adjust based on the data.

‣
What is your hourly rate?

I usually charge between $115 and $140 per hour, depending on project length and scope. Typically I reserve one to two days per week for a client.

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What does a typical collaboration with you look like?

That depends on what the team needs. But an ideal setup usually starts with a kick-off to define goals and KPIs, followed by a quick audit of your current marketing approach. From there, I’ll propose an action plan and we run a short pilot to test the collaboration. If there’s a good fit, we move to a fixed rhythm of 1 or 2 days per week, with weekly check-ins. I also support one-off projects or audits when that’s more appropriate.

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What are the advantages of a freelancer over an agency?

Agencies tend to add layers: more meetings, higher rates, less speed. With a freelancer you get one senior contact who does the work, moves fast and stays involved. An all-round marketing freelancer also saves the hours you’d otherwise spread across multiple agencies or in-house roles.

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Do you work with every type of company?

I don’t limit myself to a sector; what matters is a strong product and clear growth ambition. Recently I’ve focused on SaaS and app teams in education, social media, HR tech and FinTech, serving both B2B and B2C markets.

Get in contact

👉 Book a free video call or call me directly at +31683329344.

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