UI Engineer II

Build with us

Since 2004, we've had one clear goal: to make payments and money management effortless for every business in Europe. Today, more than 250,000 companies use Mollie to get paid, manage money and grow – with products designed to be simple, scalable, and dependable.

With 950+ Mollies across 14+ locations, we care deeply about autonomy and craft. So we work in small teams, with real ownership, and we trust you to make the right decisions. We're building for the long term, so we provide the tools you need, processes you can rely on, and a balanced work environment to help you do work you're proud of. Sound like your kind of place? Let's build together.

Your impact

The AppCore team sits at the heart of Mollie's Merchant Experience domain, owning the foundations that every other engineering team builds on. That means the mobile app, the web portal, and all the surfaces where merchants onboard, manage payments, and access Mollie's services. When AppCore works well, every team at Mollie moves faster.

We care deeply about quality and well-designed experiences, not only for our customers, but especially for the engineers building Mollie's products. This means creating clean, well-documented APIs, reliable tooling and smooth workflows that make development, testing, localisation, and releases easier and more predictable. As a UI Engineer, you bridge the gap between platform capabilities and the teams that rely on them, working across the frontend, backend and infrastructure as needed.

This is not a role where you ship one feature and move on. You are building the infrastructure that enables everything else. The team is small, growing, which means real ownership, real visibility, and the chance to shape how Mollie engineers work for years to come.

What you'll ship

• Scale the mobile app architecture to support growing user demand, with a focus on quality and long-term maintainability.
• Accelerate the app release cadence by improving and owning the release process.
• Build reusable patterns, tooling, and documentation that allow engineers across all domains to contribute to the mobile app without needing deep mobile expertise.
• Improve translation quality and localisation workflowsg, making the app accessible and accurate across all supported markets.
• Strengthen testing practices and automation across the platform, raising the bar for reliability and reducing the risk of regressions.
• Support debugging and feature delivery for teams across Mollie, acting as a platform partner to product teams who depend on the AppCore foundations.

What you'll bring

• 4+ years of experience developing mobile apps and web applications.
• Solid hands-on experience with React Native, or strong React experience combined with a clear appetite and aptitude for mobile development.
• A genuine, deep understanding of JavaScript and React fundamentals at a low level, not just surface familiarity with the frameworks.
• Experience with CI/CD pipelines and app release processes, including familiarity with how builds, deployments, and release coordination work in practice.
• A track record of building or maintaining products at medium to large scale, where code quality, reliability, and performance actually matter.
• Strong communication skills and comfort working across multiple teams and stakeholders.
• Always Be Shipping mindset: consistently delivering value to customers, where speed and quality go hand in hand.

Grow your way

At Mollie, growth is personal. We believe everyone should have the chance to develop their skills, explore new challenges and shape their career on their own terms.

You'll get regular feedback and performance reviews to support your development, with fair and transparent salary reviews along the way. Many Mollies move into new roles or take on new projects to stretch themselves, and we actively hire from within to help you take the next step.

No matter if you're aiming for promotion, exploring a different career path or building new skills, you'll be supported with the tools, trust and opportunities to grow your way.

Unlock your full potential and join us to eliminate financial bureaucracy If you're excited by the idea of building what's next, for yourself and for thousands of businesses across Europe, we'd love to hear from you. Apply with your CV (in English) using the form below.

Want a peek behind the scenes? Check out what life at Mollie is really like.

AI at Mollie

We believe in Always Be Shipping, and AI brings that philosophy to life across every team, every role, every day.

AI is core to how we build. It helps us move faster, simplify work and make smarter decisions, creating real impact for the businesses we serve. We're looking for people who are excited to use AI to shape the future of finance with us.