Our Team

Exercism is built by people from all over the world 🙌

Over 6,000 contributors
231 countries
287 GitHub repositories

A world map containing avatars of Exercism contributors

Thousands of people have supported our vision and helped build Exercism.

Exercism relies on leadership team and staff, a wider team of approximately one hundred maintainers and key contributors, and small contributions from thousands of individuals. Beyond these contributions to our product, tens of thousands of members of our community have contributed by giving feedback and help to others.

Leadership Team

Our leadership team manage the strategic and organisational sides of Exercism. They are responsible for fulfilling our mission statement and maintaining our values.

An image of Katrina

Katrina Owen

Co-founder & Director

Katrina is the original creator of Exercism. She is co-author of 99 Bottles of OOP. Polyglot developer and Ruby Hero award winner, with a degree in Molecular Biology. Cares deeply about open-source and contributes to several projects outside of Exercism.

An image of Jeremy Walker

Jeremy Walker

Co-founder & CEO

Jeremy is an entrepreneur and software developer, who's passionate about equality and opportunity. He has co-founded various organisations, including Meducation, Wondr Medical, and Kaido, and holds a patent for AI used in heart surgery.


Our staff manage our website, the CLI and the operational side of Exercism, ensuring that we provide a safe and reliable experience for everyone using Exercism.

An image of Erik Schierboom

Erik Schierboom

Head of Open Source

Erik is a polyglot developer who loves learning new languages. He builds the software and infrastructure that powers the open-source elements of the platform, ensuring each track is a joy to work with. He was a top Exercism volunteer before joining full-time.

An image of Aron Demeter

Áron Demeter

Front-end Developer

Áron is a self-taught developer who gets excited about discovering interrelations between things. He has a Master's degree in classical piano performance. In his freetime he enjoys spending time with his family, learning new languages on Exercism or listening to an opera.


People who have previously worked full-time at Exercism and since moved onto new adventures. Their legacies are gratefully remembered!

An image of Nicole Chalmers

Nicole Chalmers

Nicole is the Head of Product at Kaido. She spent two years as Head of Product for Exercism, guiding us from v1 to v2, and helping set the principles and ideas that still drive Exercism today.

An image of Charles Care

Charles Care

Charles was part of the team that built Exercism v2, working specifically on the server-side code and infrastructure. He helped build out the first version of our automated mentoring platform, and Github integration.

An image of Karlo Soriano

Karlo Soriano

Karlo worked on the website part of Exercism. He created most of the website's interactive frontend for v3, and contributed to much of the Rails backend platform.

An image of Taiyab Raja

Taiyab Raja

Taiyab is designer behind the beautiful visuals and UX of Exercism v3. He enjoys all things startups, design and entrepreneurship.

An image of Loretta Murray

Loretta Murray

Loretta was Exercism's Head of Fundraising during 2022-2023. She's motivated by the transformational power of fundraising and is a qualified business coach with a passion for developing fundraisers' skills.

An image of Jonathan Middleton

Jonathan Middleton

Jonathan was Exercism's Community Manager during 2022-2023. He loves connecting with people and hearing stories of how people are where they are in life. He is curious to learn and has been slowly getting to grips with programming.

Track Maintainers

Our maintainers are the lynchpins of the language tracks and exercises on Exercism. They create and organize exercises for each of our 50 languages and help guide us to ensure Exercism teaches students in the most idiomatic way possible.

See all Exercism maintainers


Our mentors are the human element behind Exercism, providing empathetic feedback on learners' solutions. They are the magic that makes Exercism come alive.

See all Exercism mentors

Open source contributors

Exercism could not be the success it is without the contributors of over 2,000 volunteers, who add value in numerous ways, from writing tooling to creating the exercises you solve.

See all contributors