Sixtyfour, a Y Combinator-backed startup, is hiring Software Engineering Interns in San Francisco. The role offers $6K-$10K monthly pay for junior and above level candidates. Interns will build AI agents for open-source intelligence (OSINT) and deep web research, designing systems that scale. The company emphasizes deep problem understanding, spending 80% of time on design and planning before coding. Key responsibilities include building AI research agents, owning system architecture, shipping features end-to-end, and writing evals to measure model performance. Candidates must have strong engineering fundamentals, system design skills, and proficiency in Python or TypeScript. The stack uses Python for backend/AI and TypeScript/React for product development. Nice-to-haves include OSINT experience, LLM/agent projects, and distributed systems knowledge. The role requires in-person work in San Francisco and offers real ownership, mentorship from experienced engineers, and access to top-tier LLM tools. Applicants should showcase projects they've built and be ready to discuss design decisions and scalability considerations.

The position targets students at junior level and above, welcoming strong students, new grads, and early-career engineers. Sixtyfour builds AI research agents that discover, link, and reason over information about people and companies, turning intelligence into automated research workflows for sales, recruiting, and marketing teams.

Interested candidates should apply by showing their work and demonstrating genuine curiosity about LLMs and agents. The company values how candidates think about problems over specific tool familiarity, and will teach the stack to qualified applicants.