• Entwicklung und Weiterentwicklung einer modernen Payment-Plattform für E-Commerce- und POS-Anwendungen • Konzeption und Umsetzung skalierbarer Backend-Services und APIs • Integration führender Zahlungsanbieter und Payment-Services • Gestaltung robuster Prozesse für Webhooks, Routing, Fehlerbehandlung und Transaktionsverarbeitung • Enge Zusammenarbeit mit Produkt, Architektur, Security-Experten und Management • Technische Mitgestaltung der Plattformarchitektur und relevanter Technologieentscheidungen • Erstellung technischer Dokumentationen und API-Spezifikationen für Partner und Kunden • Sicherstellung hoher Qualitäts-, Sicherheits- und Performance-Standards

• Drive system design and architecture decisions for scalability, performance, and maintainability. • Design and develop applications across backend (Java, Spring Boot, APIs), frontend (React/Angular), and database (PostgreSQL). • Act as a technical point of contact and translate business requirements into solutions. • Conduct regular code reviews and enforce standards to ensure performance, security, and maintainability. • Identify, troubleshoot, and resolve complex system and application issues. • Work with product, QA, DevOps, and business teams to ensure seamless delivery. • Mentor developers, assign tasks, and ensure timely delivery. • Participate across the full software lifecycle, including planning, design, development, testing, and deployment. • Implement testing strategies using tools like JUnit, Cypress, and Playwright. • Follow Agile best practices and proactively address vulnerabilities. • Stay updated with technologies and improve development processes and architecture. • Take on additional tasks and responsibilities as needed to support team objectives and ensure the success of the project.

Role Description We are looking for a Senior Python Backend Developer (Services) to join our engineering team and contribute to the evolution of our service layer architecture. This role is focused on designing and building reliable, scalable microservices while also working with and gradually transforming legacy systems. You will play a key role in extracting business logic from existing codebases and reimplementing it into modern, maintainable Python services. This is a hands-on engineering role requiring strong problem-solving skills, attention to detail, and a deep understanding of backend systems reliability. Success in this role means going beyond “it works” ensuring correctness, resilience, and long-term maintainability. Location: Remote from Poland (Contractor arrangement) or Cyprus Onsite (Relocation support provided) Reporting to: Technical Lead What you will do: - Legacy Modernisation: Read legacy code (PHP, Perl, or JavaScript), extract the business logic, and reimplement it correctly within a modern microservices architecture. - Reliability First: Ensure idempotency, data integrity, and graceful error handling across all services — "almost working" is never good enough. - Greenfield & Refactoring: Split your time between building new features from scratch and refactoring existing legacy modules into clean, maintainable code. - API Engineering: Design and consume external APIs with a deep understanding of webhooks, callbacks, and complex retry policies. - Agile Collaboration: Maintain clean and strong English communication to effectively collaborate with multiple stakeholders across departments working in agile sprints. - Product Thinking: Go beyond the "what" and "how" of the code — bring a product-focused mindset to understand the business logic and end-user impact of what you build. - Infrastructure Contribution: Contribute to CI/CD pipelines, Docker, or Kubernetes infrastructure where relevant. If you have a passion for infra, you are more than welcome to bring it. - Innovation: Propose and advocate for tools or technologies that can demonstrably improve our performance, security, or development speed. Qualifications - Python Mastery: 5+ years of backend engineering experience with strong Python expertise. Deep AsyncIO proficiency — you must be comfortable building non-blocking, high-reliability microservices. - Framework Expertise: Production-grade experience with FastAPI (not just familiarity). - Databases: Experience with MySQL and/or PostgreSQL — query design, schema understanding, and migration strategies. - Testing Discipline: Experience writing unit and integration tests (pytest preferred). - API & Reliability Patterns: Expertise in designing and consuming external APIs with a deep understanding of webhooks, callbacks, and complex retry policies. - Ownership Mindset: Willingness to take full ownership of high-traffic, always-up applications and operate independently within an established architectural vision. - Confidence in Complex Systems: Comfortable in complex distributed environments where reliability is non-negotiable. - Clean & Intentional Code: We value deep engineering logic over AI-generated snippets. You must be able to explain the reasoning behind every line you ship. - Curiosity for Product: You care about the "why" behind a feature — how it works for the end-user and what it means for the business. - Strong English: Both written and verbal to collaborate effectively across multi-functional teams. Requirements - Experience with PHP, Perl, or JavaScript — a strong bonus signal for legacy comprehension. - Kafka / Redis experience. - Docker / CI/CD / Kubernetes familiarity. - Financial industry exposure — fintech, payments, 3DS, Token Management Systems, or payment gateway integrations. - Track record of successfully migrating systems from one language or paradigm to another. Hiring Process - Step 1: Initial Interview – A 30–40 minute online interview with a Talent Acquisition Partner where we explore your experience, career goals, motivations, and overall fit for the role. This is your chance to walk us through your background and highlight your key achievements. - Step 2: Live Technical Assessment Interview: A live coding challenge with our team lead and designated field technical experts to assess your technical skills, the interview time will be from 60-90 minutes. - Step 3: Final Discussion – A 30-minute conversation with the CTO, CPO, Team Lead, and Talent Acquisition Partner to clarify any remaining questions about responsibilities, the domain, or the scope of the role. This is also your opportunity to learn more about our culture and expectations. Benefits - Grow with Us: Annual Learning Budget for professional development (eligible after probation)—because your growth is our growth. - Celebrate Together: We bring colleagues from all offices together for unforgettable company celebrations. - Global Collaboration & Events: Opportunities to participate in international company events and initiatives, connecting with colleagues from all regions and contributing to a truly global community.

• Own the reliability, performance, and scalability of Extensions capabilities end to end • Design and build distributed workflows that are efficient, reproducible, and observable in production • Collaborate closely with Data Scientists on the team to deeply understand requirements and translate them into engineering decisions • Identify and resolve performance bottlenecks, ensuring Extensions capabilities meet the latency and throughput demands of enterprise deployments • Contribute to architectural decisions around how Extensions integrates with the broader NEXUS backend • Write clean, well-tested Python code and hold a high bar for code quality across the team • Contribute to internal engineering documentation and help establish best practices for backend development within the team