Senior Software Engineer, Internal Tools

Salary Competitive

About the job

You’ll be joining a high-performing and rapidly expanding team of engineers at one of Denmark’s fastest-growing companies. Together, we’re building and scaling the internal platforms that power our growth—including CRM system, sales tools, and operational software used daily and enabling our commercial organization to operate efficiently at scale as we continue our European expansion.

This is an opportunity to be part of a company that has grown from startup to unicorn at record speed. As we continue to expand into new markets and serve an ever-growing customer base, you’ll work on challenges that come with operating products at scale. You’ll have significant ownership, the freedom to drive technical decisions, and a direct impact on the solutions used by businesses every day. As we grow, so will your opportunities to develop your skills, take on new responsibilities, and help shape the future of commerce across Europe.


What you'll do

  • Design and deliver scalable, maintainable, and high-quality solutions that drive business impact

  • Enhance and evolve core internal systems to improve reliability, performance, and user experience

  • Continuously optimize CI/CD pipelines and infrastructure to accelerate delivery and increase stability

  • Collaborate closely with internal stakeholders to shape ideas, define requirements, and turn them into actionable plans

  • Lead cross-functional projects from concept to successful delivery

  • Mentor and support team members, fostering technical growth and engineering excellence

  • Drive architectural improvements and champion best practices to ensure the platform scales for the future


Who you are

  • 5+ years of professional software engineering experience

  • Strong experience designing and operating distributed systems

  • Demonstrated ability to lead technical projects involving multiple engineers and influence architectural decisions

  • Experience building scalable backend platforms and APIs

  • Comfortable navigating ambiguity with pragmatism and helping shape new products and systems

  • Strong communication and collaboration skills

We don't expect experience with every technology listed below. We're looking for engineers who can learn quickly and help us build great products.


Backend

  • Java, Spring Boot

  • MySQL

  • REST APIs & Event-Driven Architecture

  • Domain Driven Design

  • Docker, AWS


Frontend

  • TypeScript

  • React

  • TanStack Query

  • Jest

  • Playwright

  • i18n


Platform & Delivery

  • GitHub Actions

  • CI/CD

  • AWS ECS

  • Observability & Monitoring

  • Feature flags


Why Flatpay?

You’ll help build and scale our internal platform, creating tools that empower teams across Flatpay and shape the future of how we operate, and scale our products.

We offer an inclusive environment where engineers are trusted with ownership and encouraged to make an impact. Our engineering teams work together from our Copenhagen office. We believe that close collaboration, quick feedback loops, and solving problems side-by-side help us build better products, move faster, and create a stronger engineering culture. We also provide plenty of perks including free slush ice, an on-site gym, a fully equipped gamer room, and much more. If you are ready to be part of this exciting journey, we would love to hear from you today.

Perks and benefits

This job comes with several perks and benefits

Near public transit
Near public transit

Free office snacks
Free office snacks

Paid holiday
Paid holiday

Free coffee / tea
Free coffee / tea

Work life balance
Work life balance

Flexible working hours
Flexible working hours

See all 18 benefits

Working at
Flatpay

WHAT IS FLATPAY? At Flatpay, we believe that merchants deserve a payment solution that is easy to understand, affordable, and free from hidden fees. That's why we offer a straightforward pricing model with no setup fees for terminals, no subscription fees, and a flat rate for all card types. It's a breath of fresh air compared to the complicated and confusing pricing structures of our competitors. ‍ What sets Flatpay apart is our dedication. We continuously strive to stay ahead of the curve, adapting our solutions to meet our client's evolving needs. Ready to be part of something extraordinary? WHAT's THE CULTURE LIKE? Flatpay is a fast-moving, performance-driven environment where people are trusted to take ownership from day one. We value initiative, resilience, and a strong work ethic. Our teams are collaborative and supportive, but we also set clear expectations and hold ourselves accountable to results. ‍ As a growing business, things move quickly. That means you’ll have the opportunity to take on real responsibility early, contribute ideas, and see the impact of your work directly. It also means being comfortable with change, solving problems as they arise, and continuously improving how we operate. ‍ We’re best suited to people who are motivated by challenge, enjoy working towards clear goals, and want to develop in a commercial, high-energy environment. WHY CHOOSE FLATPAY? Flatpay offers the opportunity to take real ownership, develop valuable skills, and grow your career in a fast-moving, ambitious company where performance and initiative are recognised.

Read more about Flatpay

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