👋 Hello, I'm Jan,

a people-centric CTO and

serial startup founder.

based in

About me

🌍 I live in London 🇬🇧 since 2016 and grew up in Berlin-Kreuzberg 🇩🇪🇹🇷. My mom is from Serbia 🇷🇸, and my dad is a Swabian🇩🇪. I speak more Turkish than Serbian, which doesn‘t mean much 😂.

💃 Strong females influenced my life. 💍 I am husband to a 🔬scientist and 🏋️♀️feminist (a.k.a. The Boss). My mother couldn’t write or read until she was 40 and moved from Serbia to Berlin for a better life working as a cleaner.

💾 I fell in love with React, Typescript and the Javascript eco-system, but if I had a tattoo, it would be a Ruby tattoo (my first intimate and loving relationship with programming).

📚 I love reading with a 90:5:5 ratio of non-fiction to fiction (sci-fi, fantasy, history) to learn and serve people around me.

🏀 I play street ball, 🛹 love to skate, have deep roots in Hip-Hop — as a competitive breakdancer🕺🏿and freestyle rapper 🎙 and crew head. I fought for the Horde 😈 (World of Warcraft) and defended Midgard in 👑 Dark Age of Camelot, which gave me invaluable remote leadership skills.

Get in touch

Biggest Achievement

Co-Founder at Zencargo -
Supply Chain

To build a world with more innovative trade, we built a supply chain optimisation platform to create a competitive advantage for international shippers by bringing all international trade parties closer.

I was primarily responsible for shaping product and culture at Zencargo as Co-Founder and CTO. I hired my succession when we reached 160 employees, leading teams of up to 45 people across engineering, product development, and design.

In 2021 my most significant achievement was making myself dispensable and putting the future leadership for the product and engineering team in place while securing our Series B. Digital+ Partners acknowledged my signature across Zencargo’s culture after interviewing the senior executive team, making me feel proud and accomplished.

In 2020 my most significant achievement was a voluntary turnover rate in the engineering team of only 5.56% (93.23% average quarterly retention rate), having the most extensive team and the highest e-NPS across the business while delivering for our customers to stay in business during COVID-19.

I was accountable for the technology strategy and vision while touching on all areas of our business strategy. I was the first contributor to the overall product as a full-stack engineer and successfully scaled my role with the organisation's growth.

Zencargo attracted stellar investors. I’m grateful to be part of the LocalGlobe, HV Capital and Digital+ Partners Investor Network.

Zencargo Logo

my Values

Radically Inclusive

To build psychological safety and neurodiversity

Diversity and Equity are outcomes of inclusion.

My goal is to affect the fundamental nature of leadership prevalent in the tech-startup community and probably in most of our business world.

I advocate for social change, practicing the most progressive leadership style possible through conscious inclusion, calling out unconscious bias.

Do the right thing

Ethics mean the world to me, no shortcuts.

Society even over business. Business even over team. Team even over the individual. I believe the focus on individualism is hurting our society.

With great power comes big responsibility. Technology is changing everything, so ethics can't be an afterthought.

No Gap between statements and facts

I practice radical candour and transparency.

I find it hard to work with people that intentionally say things differently than they mean.

Toxic positivity and artificial harmony are eroding trust and kill businesses, that's why I prefer high stake conversations.

I believe that meaningful relationships need drama and friction to test each other's boundaries and experience unconditional love.

I accelerate learning

Learning is crucial for me personally but also for any business to thrive.

Learning faster than the competition is the only sustainable advantage companies have to succeed.

I hated school, but I love education.

My biggest fear is to slow down learning, thinking I'm an expert or not noticing that I'm on the top of mount stupid (see Dunning-Kruger Effect).

What I'm looking for

Companies build bad data models

Business's data is tightly coupled to its product's user interface and product's database schema, which continuously change.

Join me


I'm looking for founding engineers to join me.

I'm looking for domain experts that share a passion for domain-driven design, event-storming and event-sourcing.

I am building a deep-tech product to democratise event-driven-architecture.

Get in touch if you want to revolutionise the way process-oriented businesses are built with me.


I'm looking for founding designers to join me.

I am looking for designers that are interested in programming and designing no-code and collaborative discovery experiences.

I believe there is a missing piece in the no-code world that deals with data modelling and aggregation.

Get in touch if you want to help domain experts, designers, product managers and engineers to develop and evolve a shared understanding and ubiquitous language.


I'm looking for founding marketers to join me.

I am looking for marketers that are excited about creating a new category in no-code.

I appreciate that finding the right market and channel is something I lack experience with.

Get in touch if you are excited to help identify the right positioning, channel and ideal customer profile with me.


I am looking for investors and angels with a focus on deep-tech.

I am looking for investors that demonstrate a clear focus in deep-tech and process centric businesses, e.g. health-care, manufacturing, logistics and finance.

I am excited to start my first deep-tech startup after spending the majority of my career in data-centric startups.

Get in touch if you want to learn more.

What I offer

I offer my experience for three to six months.

In order to start my new venture, I take on work as a fractional CTO for 1-2 days per week until I have fundraised for this business.

Not every startup needs an experienced CTO (thank god). I can help with hiring your early team, writing the job spec for the right CTO for your company, leading your product delivery and defining your tech strategy.

There's a lot of ways how I can help, as I am a full-stack engineer (React, Next.js , Ruby on Rails and Elixir), reach out if you want to explore this with me.

Fractional CTO

I work with your team in an operational role to drive substantial change for your business.


We meet regularly for up to three months to either work on agreed goals or give you high quality time to think with an experienced CTO.

Health Check

An intensive, one-day health check on your tech team's people, processes, code, and product. Suitable for investment due diligence, acquisition check, or internal audit.

I'm open for new offers to help.

Book a call



A decade of experience
as startup founder.


I co-founded a web development agency in Berlin as CTO with three friends from Technische University Berlin. We built 12 prototypes and products in 12 months, very intense but rewarding time.


I co-founded bonusbox, a E-Commerce loyalty platform, where we raised a Series A and had over 4 million users, 70% of which were in Brazil, 30% in Germany. This was my first VC backed startup as CTO.


I arrived in London. Started as CTO for Solar Options for Schools, which I quickly realised was not the right fit for me. I then started Zencargo in December that year with Alex and Richard. We together raised $66.4M for our Series B before I left the team. Zencargo is the hottest supply chain optimisation startup in Europe.


I left Zencargo in March 2021 to explore new opportunities. I co-founded Kaizera that ended up with a founder breakup after only six months (what an experience).


I am starting a new business.

Picture of Jan Riethmayer


Send me a text first, as I don't answer unknown numbers