Software Engineer Amsterdam • KnappeKoppen

We are growing fast. Our ambition is to become Europe’s one-stop shop for supplements: every brand, every goal, all in one place. We do this with a tech-first approach. Most of our systems are built in-house, and the majority of our team has a technical background.

We live by the motto “automate everything that can be automated.” That mindset allows us to achieve €3 million in revenue per FTE, which is far above industry standards. For us, it has become a challenge in itself: staying lean and efficient while competing directly with the biggest players in the market.

We are a young and dynamic team with an average age of 23. Work hard, have fun might sound cliché, but it is how we work. We push ourselves to build something great while always keeping room for laughter and good energy.

Every day, thousands of customers across Europe rely on our platform. Now we are aiming for the next milestone: scaling our company to €100 million in revenue. To get there, we are looking for a Software Engineer (.NET / React) who can help us make our platform more scalable, smarter through automation, and ready for the future with AI.

• Maintain and improve our existing backend platform built on .NET (C# / ASP.NET).
• Design and implement new backend features that support business needs and accelerate growth.
• Work with Shopify APIs and other third-party integrations to optimize e-commerce workflows (inventory, orders, fulfillment, payments).
• Ensure scalability and reliability of our systems on PostgreSQL and Google Cloud Platform.
• Collaborate with the team to introduce automation and AI solutions that make our operations smarter and more efficient.
• Occasionally contribute to frontend development in React / Next.js to connect backend features seamlessly with the customer experience.
• Provide guidance, mentorship, and technical leadership to fellow developers.

• Proven experience as a software engineer with advanced .NET (C# / ASP.NET) skills.
• Strong understanding of e-commerce workflows and system integrations.
• Hands-on experience with Shopify APIs and other third-party systems.
• Solid knowledge of PostgreSQL and cloud platforms (preferably Google Cloud Platform).
• Familiarity with automation workflows and AI integration.
• A problem-solving mindset with the ability to design scalable and efficient solutions.
• Strong communication skills and the ability to mentor and guide other developers.
• Willingness to work from our office in Oostzaan at least 4 out of 5 days.
• Experience with React or Next.js is a plus.

• A competitive salary between €2.915,47 and €4.518,80 gross per month, depending on experience (excluding 8% holiday allowance and pension contribution).
• 23 vacation days based on full-time employment.
• A well-arranged setup with high-end hardware.
• A catered and paid-for lunch every day.
• Flexible working hours (start between 8 and 10 AM).
• The possibility to work from home one day a week.
• Pension contribution.
• Travel allowance.
• Gym membership reimbursement.
• Internet allowance.
• Christmas package and birthday gift.
• Regular company outings and team drinks.
• Working in a young, dynamic team with an average age of 23.
• A direct say in key decisions. You will be shaping our platform at the highest level, with no layers above you.