Hypercubic

Founding Software Engineer - Backend

San Francisco | OnSite

Founding Software Engineer - Backend San Francisco | OnSite We are looking for a founding backend engineer with unusually strong engineering and design taste. The world's most critical infrastructure-banking, airlines, utilities-is held together by millions of lines of COBOL and mainframe logic written decades ago. The engineers who built it are retiring and the documentation is fading. These systems are "too big to fail" and "too complex to change," leaving global infrastructure frozen in the 1970s. At Hypercubic, we're building AI systems that can understand, reason about, and rearchitect large-scale legacy applications. We work at the intersection of program analysis, knowledge extraction, and agentic systems, applied to some of the most critical enterprise software in the world. Learn https://www.hypercubic.ai/insights/mainframe-modernization-is-a-hard-and-fun-problem-to-solve why we're excited about mainframe modernization. ABOUT THE ROLE We're looking for a backend engineer with unusually strong engineering and design taste. You will work directly with the CTO to design, prototype, and productionize AI-powered systems from first principles. This is a founding role with meaningful ownership over architecture, product direction, and engineering culture. It is suited for someone with strong fundamentals and comfortable operating across abstraction layers, from low-level system reasoning to high-level interactions. WHAT YOU'LL DO - Rapidly prototype new concepts and features to validate ideas before full implementation. - Ship AI-driven features end to end, from model interaction to user-facing workflows. - Set early engineering standards around testing, reliability, and code quality. - Translate ambiguous problem statements into concrete experiments, constraints, and working systems. - Lead architecture decisions