Principal Software Engineer

Financial technology is a high-growth industry as change and innovation continue to disrupt the status-quo and prompt major transformation. Arcesium is at a particularly interesting time in our own growth as we look to leverage our successfully established market position and expand operations in pursuit of strategic new business opportunities. We value intellectual curiosity, proactive ownership, and collaboration with colleagues, and we empower you to meaningfully contribute from day one and accelerate your professional development.

We're looking for a Principal Software Engineer who keeps a large, distributed platform fast, stable, and efficient as load and complexity grow. This is a role based in our Stockholm office, embedded in a team that owns and operates what it builds.

• →Own projects end-to-end from an architectural standpoint - driving them independently from requirement-gathering through design, delivery, and operation, with minimal oversight.
• →Gather and validate requirements, translate them into high-level and low-level designs, and raise the quality bar on designs produced by others.
• →Make, document, and review architectural decisions, articulating trade-offs clearly to both technical and non-technical stakeholders.
• →Own non-functional attributes - performance, stability, scalability, and availability - and ensure systems meet internal standards.
• →Profile real production systems, identify bottlenecks, manage memory and resource usage, and tune latency and throughput across distributed, event-driven services.
• →Level up the people around you - share knowledge, review designs, and influence both technical and business decisions in the right direction.

• Senior-level experience building and operating production software.
• A track record of architecting, building, and running distributed systems at real scale: cloud, Kubernetes, event-driven architectures.
• Strong performance-engineering background: profiling, benchmarking, memory management, concurrency, and tuning systems under real production load.
• The ability to make architectural decisions and explain trade-offs to engineers and non-engineers alike.
• Strong fundamentals: system design, data structures, concurrency, and API design.
• Clear communicator who enjoys making the people around them better.