Staff Engineer - Payment

Shine is the financial copilot for entrepreneurs and small business owners. Founded by serial entrepreneurs Rico Andersen and Martin Hegelund, Shine is a leading European fintech unicorn on a mission to restore the joy of running a business, by ending wasted time on financial admin. Shine offers a connected solution for invoicing, accounting, payroll, business accounts, payments, and financing, meaning business owners can focus their energy on growing a healthy business, not held back by manual admin. Part of something bigger Today we're part of Cegid, a European leader in cloud software for finance and accounting. Together we're building Europe's leading financial copilot for small businesses and their accountants. Shine already supports more than 400,000 small businesses. As part of Cegid, we now reach over one million small businesses and 15,000 accountants across Europe. We're a multicultural team working from France, Germany, Denmark and the Netherlands, contributing to a wider European network that spans Spain, Portugal and Belgium. Your hiring experience matters Just as we respect our customers' time, we respect yours. Your experience with Shine and Cegid should feel simple, transparent and genuinely supportive. If this sounds like somewhere you want to grow, we'd love to hear from you. Your Role as a Staff Engineer - Payments In this role, you will be a key technical leader, responsible for the architectural governance and strategic direction of our cloud-native payment gateway. You will focus on driving correctness, strong transactional guarantees, and reconciliation for a scaling financial service operating under stringent EU financial regulator expectations. Your work will ensure our platform remains highly optimized, secure, and fully compliant with PCI DSS standards. Our architecture is built for the modern era: a serverless-ready microservices ecosystem leveraging Google Cloud's serverless and managed services to deliver low-latency, high-throughput solutions for SMB merchants across Europe. Our Technical Landscape: Backend Framework: Spring Boot, Spring WebFlux, Project Reactor (Non-blocking I/O) Infrastrucure: Google Cloud Run, CloudSQL (PostgreSQL), Firestore, Pub/Sub, Cloud Tasks API Standards: Contract-First API Design using OpenAPI specifications Database Management: Liquibase (Decoupled migrations), Spring Data R2DBC Complilation/Runtime: GraalVM Ahead-Of-Time (AOT) compilation, "scratch" Docker images Architecture: Classic 3-Layer (Controller, Service, Repository) with MapStruct DTO mapping Your responsibilities will include: Architectural Leadership: Define and drive the high-level architecture of core payment systems (gateway, ledger, payment orchestration), contribute to Architecture Decision Records (ADRs), and ensure strong guarantees around consistency, correctness, auditability, and reconciliation across all asynchronous flows. Technical Excellence: Oversee technical execution, conduct rigorous code reviews, and ensure the implementation aligns with our core design principles, such as Reactive Programming and Contract-First design. Team Leadership & Mentorship: Lead, manage, and mentor the hybrid core and extended delivery teams (onsite and remote), ensuring technical alignment, fostering a culture of high performance, and leading technical discussions and workshops to build a shared understanding of system design and domain complexity. Compliance & Security: Maintain strict PCI DSS compliance through patterns like secure credential injection via environment variables and Secret Manager integration. Strategic Delivery: Partner with Product Managers to define roadmaps for critical components, including BIN Lookup services, Surcharging engines, and Dynamic Currency Conversion (DCC). Operational Optimization: Drive the evolution of our CI/CD pipelines and deployment strategies to Google Cloud Run to ensure zero-downtime horizontal scaling. Core Design Principles You Will Champion Reactive Everything: Ensuring a completely non-blocking execution model from the controller down to the reactive database driver. Contract-First Development: Guaranteeing implementation honors the API contract without drift through auto-generated reactive Java interfaces. Immutable Infrastructure: Utilizing GraalVM and "FROM scratch" Docker images for ultra-lightweight, secure binaries. Event-Driven Resilience: Utilizing Google Pub/Sub and Cloud Tasks for asynchronous status processing, rate limiting, and automatic retry logic. 📍 Job located in Copenhagen with possibility of two remote working days per week. About you Extensive experience in software engineering leadership (Staff, Principal, or Lead Architect level). Expertise in Java, Spring Boot, and Spring WebFlux / Project Reactor. Deep experience with Google Cloud Platform (GCP), specifically Cloud Run, Firestore, and Pub/Sub. Proven track record in the payments industry, with a deep understanding of PCI DSS requirements and financial calculation accuracy. Experience with database versioning tools like Liquibase and reactive database drivers (R2DBC). Strong communication skills to manage stakeholders and lead cross-functional delivery teams. Deep expertise in distributed systems design, including trade-offs between consistency, availability, and operational complexity, and experience designing systems with strong transactional and correctness guarantees. Practical domain experience with core payment concepts such as intelligent routing, reliable reconciliation processes, and auditability requirements in regulated environments (e.g., EU banking regulators/SEPA rails) is a strong plus. Equal Opportunity Employer We follow the principle of equal treatment to consider all job applicants and do not discriminate based on their gender, sexual orientation, color, racial or ethnic origin, religion, disability, etc. as per applicable law. Our recruitment process 1️⃣ A 30' first call with Talent Acquisition to get to know you better and share more about Shine. 2️⃣ A 60' interview with the Hiring Manager to discuss your past experiences and the role we are offering. 3️⃣ A 60' business case presentation to highlight your skills and give you a hands-on feel for the role. 4️⃣ A 30' team introduction, followed by a soft skills interview to see how we can best support your growth at Shine.