Senior Software Engineer, Online

Flatpay

ABOUT THE JOB Flatpay has become one of the fastest-growing payment companies by helping merchants accept payments in-store and online. But with 100,000+ merchants relying on us today, payments are only part of running a business — every transaction eventually needs to land in the books, and that's still far too much manual work. Accounting and Bookkeeping is one of Flatpay's most strategic engineering domains. We're building the products and platforms that turn transaction data into clean books and accurate financial records — including integrations with the accounting systems our merchants already use. As a Senior Software Engineer, you'll play a key role in defining the technical direction of Flatpay's accounting platform — from how we model financial data, to how we build systems that handle real-world bookkeeping at scale and connect reliably with the third-party systems on the other end.This is an opportunity to join a company that has grown from startup to unicorn at record speed. You'll have significant ownership, the freedom to drive technical decisions, and a direct impact on tools that 100,000+ businesses can rely on. As we expand across markets — each with its own accounting practices, tax rules, and reporting requirements — you'll help shape how Flatpay scales financial infrastructure. If you care deeply about the accuracy financial data demands, this is a domain where your work will play a central role in Flatpay's future growth. WHAT YOU'LL DO * Design and build scalable systems that power Flatpay's accounting and bookkeeping capabilities * Lead feature and platform initiatives involving multiple engineers, driving delivery from discovery through production * Take ownership of features from design and implementation through deployment and maintenance * Drive architectural decisions and long-term technical improvements * Build APIs, services, and data models that handle financial data accurately and at scale * Improve reliability, observability, performance, and security across the platform — with particular attention to the accuracy and consistency that financial data requires * Partner with engineers, product managers, and stakeholders to drive technical and product outcomes * Help establish engineering standards and best practices as the Accounting and Bookkeeping domain continues to grow WHO YOU ARE * 7+ 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, especially ones that integrate with internal and third-party systems * Comfortable navigating ambiguity and helping shape new products and systems * Strong communication and collaboration skills * Experience within payments, accounting and bookkeeping systems, or financial data platforms is a plus You'll be working with technologies such as the following. 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, feature flags Platform & Delivery * GitHub Actions * CI/CD * AWS ECS * Observability & Monitoring WHY FLATPAY? As part of our team, you'll join 2,000+ passionate Flatpayers dedicated to shaping the future of payments. You'll help build a strategic new business area from the ground up, working on products that directly connect merchants and consumers while shaping the future of online payments at Flatpay. 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're ready to help build and scale the future of payments, we'd love to hear from you.

Flatpay

ABOUT THE JOB Flatpay has become one of Europe's fastest-growing payment companies by helping merchants accept card payments in-store. Our Point of Sale system serves as the central engine of the business. It streamlines the merchant's entire workflow — from order taking, product and inventory management, to payment processing, reporting, and compliance. Some of the core capabilities include: * Product catalogue: Organizes how they manage their products, categories, modifiers and inventory * Order management: Basket, pricing, discounts, payments and managing tables and long-running orders among groups of customers.  * Hardware integrations to barcode scanners, receipt and kitchen/bar printers and our different Mobile-, Premium- and Basic POS devices. No least manage synchronicity across multiple POS systems at shared locations in realtime. * Our reporting suite ensures cash management, end-of-day reports, various sales, turnover, staff, tax and compliance reports that enables merchants to optimize their business and comply with local tax regulations. As our merchants grow, so does the platform. Every new market introduces new payment methods, fiscal requirements and merchant needs. Every new feature increases the depth and complexity of the product. And with our customer base doubling approximately every six months, the demands on scalability, reliability and performance continue to grow. This is a hands-on engineering role with significant ownership. You'll influence technical direction, contribute to architectural decisions and solve the engineering challenges that come with building one of Europe's fastest-growing commerce platforms. WHAT YOU'LL DO As a Senior Android Engineer, you'll contribute far beyond implementation. You'll help shape technical direction while remaining deeply involved in building products. You'll work closely with Product, Design and fellow engineers to build software that scales across all dimensions: more merchants, more markets, more capabilities and increasingly sophisticated workflows. Your responsibilities will include: * Designing, building and evolving features across our Point of Sale platform platform. * Lead feature and platform initiatives involving multiple engineers, driving delivery from discovery through production * Build and maintain features in the Android POS platform in Kotlin/Compose that connects to printers, payment terminals and utilizes real–time communication via AWS MQTT.  * Take ownership of features from design and implementation through deployment and maintenance * Drive architectural decisions and long-term technical improvements * Improve reliability, observability, performance, and security across the platform * Mentor engineers through coaching, code reviews, and knowledge sharing * Continuously improving our engineering practices, tooling and development experience * Contribute to testing, operational excellence and contribute to a collaborative team culture  WHO YOU ARE We're looking for experienced engineers who enjoy solving difficult problems and helping others succeed. You likely bring: * 7+ 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 * Comfortable navigating ambiguity and helping shape new products and systems * The ability to break down complex problems into pragmatic, maintainable solutions. * Strong communication and collaboration skills * Experience building scalable backend platforms and APIs * Continuously improve CI/CD pipelines * A collaborative mindset and a willingness to challenge ideas constructively * Contribute to testing, operational excellence and contribute to a collaborative team culture * Experience within payments, fintech, e-commerce, SaaS, or high-scale transaction systems is a plus You'll be working with the following technologies; we don't expect experience with every technology listed; we're looking for engineers who can learn quickly and help us build great products. * Kotlin, Android, Java  * Jetpack Compose, MVVM  * Dagger Hilt, Room, DataStore * Retrofit, AWS MQTT * JUnit, Espresso, Robolectric * CI/CD with GitHub Actions * Targeting hardware such as scanners, printers & payment terminals. WHY FLATPAY? As part of our team, you'll join 2,000+ passionate Flatpayers dedicated to shaping the future of payments. You'll help build a strategic new business area from the ground up, working on products that directly connect merchants and consumers while shaping the future of online payments at Flatpay. 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're ready to help build and scale the future of payments, we'd love to hear from you.

Flatpay

ABOUT THE JOB Flatpay has become one of Europe's fastest-growing payment companies by helping merchants accept card payments in-store. Our Point of Sale system serves as the central engine of the business. It streamlines the merchant's entire workflow — from order taking, product and inventory management, to payment processing, reporting, and compliance. Some of the core capabilities include: * Product catalogue: Organizes how they manage their products, categories, modifiers and inventory * Order management: Basket, pricing, discounts, payments and managing tables and long-running orders among groups of customers.  * Hardware integrations to barcode scanners, receipt and kitchen/bar printers and our different Mobile-, Premium- and Basic POS devices. No least manage synchronicity across multiple POS systems at shared locations in realtime. * Our reporting suite ensures cash management, end-of-day reports, various sales, turnover, staff, tax and compliance reports that enables merchants to optimize their business and comply with local tax regulations. As our merchants grow, so does the platform. Every new market introduces new payment methods, fiscal requirements and merchant needs. Every new feature increases the depth and complexity of the product. And with our customer base doubling approximately every six months, the demands on scalability, reliability and performance continue to grow. This is a hands-on engineering role with significant ownership. You'll influence technical direction, contribute to architectural decisions and solve the engineering challenges that come with building one of Europe's fastest-growing commerce platforms. WHAT YOU'LL DO As a Senior Backend Engineer, you'll contribute far beyond implementation. You'll help shape technical direction while remaining deeply involved in building products. You'll work closely with Product, Design and fellow engineers to build software that scales across all dimensions: more merchants, more markets, more capabilities and increasingly sophisticated workflows. Your responsibilities will include: * Designing, building and evolving features across our Point of Sale platform platform. * Lead feature and platform initiatives involving multiple engineers, driving delivery from discovery through production * Build APIs, services, and integrations that enable stock, order lifecycle, sales reporting & compliance reporting towards governmental standards of our markets.  * Take ownership of features from design and implementation through deployment and maintenance * Drive architectural decisions and long-term technical improvements * Improve reliability, observability, performance, and security across the platform * Mentor engineers through coaching, code reviews, and knowledge sharing * Continuously improving our engineering practices, tooling and development experience * Contribute to testing, operational excellence and contribute to a collaborative team culture  WHO YOU ARE We're looking for experienced engineers who enjoy solving difficult problems and helping others succeed. You likely bring: * 7+ 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 * Comfortable navigating ambiguity and helping shape new products and systems * The ability to break down complex problems into pragmatic, maintainable solutions. * Strong communication and collaboration skills * Experience building scalable backend platforms and APIs * Continuously improve CI/CD pipelines * A collaborative mindset and a willingness to challenge ideas constructively * Contribute to testing, operational excellence and contribute to a collaborative team culture * Experience within payments, fintech, e-commerce, SaaS, or high-scale transaction systems is a plus You'll be working with the following technologies; we don't expect experience with every technology listed; we're looking for engineers who can learn quickly and help us build great products. * Java, Spring Boot, JUnit * MySQL, Flyway, SQS * REST APIs * Domain Driven Design * Docker, Terraform, AWS ECS * Ports and adapters architecture WHY FLATPAY? As part of our team, you'll join 2,000+ passionate Flatpayers dedicated to shaping the future of payments. You'll help build a strategic new business area from the ground up, working on products that directly connect merchants and consumers while shaping the future of online payments at Flatpay. 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're ready to help build and scale the future of payments, we'd love to hear from you.