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

👉 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

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

Get in contact

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