Fulltime Mainframe Jobs in Novato, CA (NOW HIRING)

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 why we're excited about mainframe modernization.
About the Role
We are looking for students with unusually high slope and strong engineering taste. You will work directly with the CTO to design, prototype, and productionize AI-powered systems from first principles.
You'll start by owning a well-scoped project that ships to production. As you demonstrate strong judgment and execution, you'll take on broader ownership. Interns who perform well may receive an offer to join Hypercubic full-time.
This role is suited for someone with strong fundamentals who learns quickly and is comfortable working across abstraction layers, from low-level system reasoning to high-level product interactions.
What You'll Do

• Own and ship a high-impact engineering project end to end.
• Rapidly prototype new concepts and features to validate ideas before full implementation.
• Build AI-driven systems, including agent workflows, evaluations, program-analysis tooling, backend infrastructure, and user-facing features.
• Translate ambiguous problems into concrete experiments, constraints, and working systems.
• Contribute to engineering standards around testing, reliability, and code quality.
• Work directly with the CTO on technical and product decisions, taking on greater ownership as you earn trust.
• Collaborate with subject-matter experts and customers across industries including banking, insurance, airlines, and utilities.

You are a Fit if...

• You care deeply about your work and the product you are building.
• You have strong programming fundamentals and can learn unfamiliar tools and systems quickly.
• You have demonstrated your abilities through ambitious projects, research, open-source contributions, internships, or exceptional coursework.
• You are comfortable with uncertainty and enjoy figuring out what to build before determining how to build it.
• You think in systems and feedback loops, not just features.
• You can move fast and slow-prototyping ideas in hours, then developing the most promising ones to a high-quality bar.
• You can reason clearly about technical decisions and communicate your thinking.
• You want to become world-class at AI engineering.
• You have a bias for action and thrive in fast-moving environments.

Nice to Have

• Experience building complex agentic products, infrastructure, or autonomous systems.
• Strong testing intuition, including experience with TDD or property-based testing.
• Experience building and maintaining production-grade software.
• Exposure to legacy systems (especially mainframes or COBOL), compilers, program analysis techniques, or high-performance computing (HPC).
• Familiarity with enterprise software constraints.

Logistics

• Eligibility: Open to currently enrolled undergraduate and graduate students of any year, degree program, or major.
• Location: This is a full-time, in-person role based in San Francisco, California.
• Timing: Start dates are flexible and applications are considered on a rolling basis. We can accommodate summer internships, semester-long internships, and co-op schedules.
• Relocation: Relocation support is available as needed.
• Work authorization: Candidates must already be authorized to work in the United States. We can support CPT and OPT, but cannot sponsor new visas.