Testimonials

Feedback from clients and former mentees on experimentation, CRO, strategic judgment and building stronger internal capability.

From clients:

Besides uplifts in conversion rates at various points of the customer journey, the project helped implement an experimentation culture in our company, which we continue to strengthen across the entire team to this day.

Dr. Laurenz Preusse

Chief Marketing Officer, PKW.de

Very strong communication, very proactive, and you can clearly see the structured, well-thought-out approach as well as the solid expertise. Rarely experienced: a team genuinely willing to go the extra mile at any time.

Johannes Sörensen

Co-Founder & CEO, ahead Nutrition

Thanks to the structured approach and clear action plan, it was easy for us to implement the CRO measures after the audit.

Elisabeth Reiter

Performance Marketing, Foodji

Working with Nils is highly enjoyable. His professional, personable and precise approach creates significant value. We exchange ideas as equals, challenge them and develop them further. In a short time, this helped me take my CRO knowledge to a higher level.

Luca Weingard

Digital Sales Performance Specialist, KPT Insurance

Selected companies:

DEFSHOP logo
ahead Nutrition logo
PKW.de logo
Rosental Organics logo
Sonova logo
GEERS logo
JACKS beauty line logo
KPT logo
MySports logo
GoldSilberShop.de logo
Foodji logo
SIRPLUS logo
eGroup logo
EVO Fitness logo
Eismann logo
AirNav RadarBox logo
OneMate logo
HeyCater logo
Dear Darling Berlin logo
Benedict Riva logo

From former mentees:

Nils gave me a useful introduction to A/B testing and how to set it up. Very knowledgeable!

Max Suttorp

Former mentee

I learned that a funnel is about way more than just the website itself. We talked a lot about the bigger picture and some of the more detailed steps in the customer journey.

Oliver Bock

Former mentee

Nils was very helpful and offered actionable insights.

Jack Findaro

Former mentee

Nils was super patient and guided me through the GA4 setup. He explained very clearly where I could find the right information. [...] I would also book another call with him!

Celina Uhl

Former mentee

Nils provided great insights and very valuable feedback about the website and how to improve it. [...] He was able to understand the challenges and provide useful tips.

Ceci

Former mentee

I now have a clear understanding of what we need to do to improve our conversion rate. [...] He tried not only to give general frameworks but understand our business and our value proposition.

Alina Hura

Former mentee

Nils has a deep understanding of organizational change and team dynamics. [...] His ability to blend strategic thinking with a genuine concern for team well-being is a rare and valuable trait.

Oliver Marques

Former mentee

Nils provided great insights into improving my website and offered valuable strategies for crafting a more engaging marketing strategy.

Marko Luznjanin

Former mentee

Nils is the vital discernment and cognitive clarity necessary within your disordered pursuits. [...]

Erik

Former mentee

Clearly very knowledgeable and passionate about CRO!

Hamza Waheed

Former mentee

I thought I needed tactical tips but got advice on culture building and change management—which is exactly what I needed.

Kamil Kaminski

Former mentee

Thanks a lot for your help, [Nils]! Your tips were super helpful!

Georgi Todorov

Former mentee

Nils was very knowledgeable and spot on in pointing out the issues with our onboarding. He even sketched out some potential solutions. [...]

Hamel Shah

Former mentee

I walked out of the session with over three pages of notes and a ton of actionable insights, including how to conduct qualitative research using competitor reviews. [...] He patiently answered all my questions and shared helpful CRO resources.

Pratik

Former mentee

Nils patiently answered all my CRO questions. He went the extra mile and even created a visual diagram showing how I could improve my website’s conversion rate. [...]

Yaseen Sadan

Former mentee

November advisory openings:

I currently have 3 advisory spots available for engagements starting in November. Book a meeting, and we’ll assess whether the engagement fits your program.

Copyright © 2026 Nils Koppelmann.