Software Engineer

Skip to main content Software Engineer XOR San Francisco Bay Area Apply Software Engineer XOR San Francisco Bay Area 1 day ago 145 applicants See who XOR has hired for this role Apply Save Report this job About XORXOR is a platform that helps world-class companies pushing the frontier of AI hire exceptional ML, RL, and AI engineering talent.About Our ClientOur client is a well-funded AI startup working on next-generation training systems for large language models. The team is small, technical, and moving fast, with a strong focus on hands-on engineering over process.About the RoleWe're looking for engineers who are keen to find where the best coding models still fail on real software work - large codebases with existing conventions and technical debt, ambiguous design decisions, multi-step problems - and build rigorous, gradeable test cases around those failures. You'll own each case end to end.What You'll DoHunt for where coding models break across software, and build the hard, high-fidelity scenarios that expose those failures and push the ceiling of what the best models can doOwn the hardest problems on the roadmap end-to-end: multi-step workflows, realistic stakeholder interactions, large codebases with real conventions and technical debt, and challenging system designBuild verification robust enough that a model can't hack it, and tell genuine capability gaps apart from artifacts of your own setupDirect coding agents heavily in day-to-day work, evaluate their output critically, and recognize when they are failing in subtle waysBuild the tooling your own work depends onMentor newer engineers on the team as it growsWhat We're Looking ForDeep software engineering experience across multiple domains, with genuine expertise in at least one specialty: infrastructure, distributed systems, performance, security, compilers, databases, or similarProficiency in PythonExtensive hands-on experience with coding agents, including an intuition for where they cut corners and how to direct them wellStrong intuition for how models behave, even without prior ML or AI experience - you can anticipate where a model will take shortcuts and design around thatComfort working independently on complex, ambiguous problems with minimal directionTrack record of owning work end-to-end in previous rolesNice to HaveSenior or staff software engineer at a company known for engineering rigor (e.g., a frontier AI company, infrastructure startup, or systems-heavy team) wanting to apply that experience to model trainingDeep specialty expertise in an area current models struggle with (distributed systems, low-level performance, security, compilers)Excited about building a new hard problem from scratch on a regular basisEarly engineer at a previous startup who shipped independently and wants to do it again in AISignificant time spent building with coding agents, writing about their failure modes, or contributing to agent evaluation work Show more Show less Seniority level Mid-Senior level Employment type Full-time Job function Information Technology Industries Software Development Referrals increase your chances of interviewing at XOR by 2x See who you know Get notified...