Software Engineer

Software Engineer: Backend & Core Systems Hollow Sun Industries · Full-time We build the operational software layer for Europe's most consequential institutions — defence, energy, healthcare, industry. THE WORK You own a domain end to end — ingestion, core application logic, the service mesh, the storage layer — and you are accountable for its correctness, latency, cost, and failure modes. Not the story points. You are involved across the entire product lifecycle: idea, design, prototype, production delivery, and the three years of operation after. You will sit with non-technical people who understand the problem better than you do, and you will translate. You debug incidents where the stack trace lies and the metrics disagree. You propose architecture in writing, get taken apart in review, and either hold your position with evidence or change it without ego. WHAT WE REQUIRE - Demonstrated proficiency in at least one systems language — Java, C++, Rust, Go — plus fluency in Python. Not exposure. Proficiency. - In-depth command of data structures, system architecture, API design for microservices, distributed systems, and consensus and consistency tradeoffs you can defend under questioning. - Experience designing, shipping, supporting and maintaining live backend systems. You have carried the pager for something you built. - Familiarity with storage and data processing systems, database internals, query planning, and cloud infrastructure. You know why your query is slow before you open the profiler. - Performance work with numbers attached. A p99 you moved by an order of magnitude, and the exact reason it worked. - Security-conscious engineering. Cloud, on-premise, and air-gapped or restricted environments are all in scope. Data sensitivity is not theoretical here. - Engineering background in Computer Science, Mathematics, Software Engineering, Physics or similar — or a body of work that makes the question irrelevant. We check the work, not the credential. - Exceptional written and verbal communication. You iterate fast, absorb feedback, and hold an uncomfortably high bar for quality. If you cannot write, you cannot work here. DO NOT APPLY IF You need the problem fully specified before starting. You measure contribution in output rather than outcome. You want the codebase to be someone else's responsibility at 2 a.m. TO APPLY Send the thing you built that you are proudest of, and one paragraph on what you would do differently now.