Software Engineer, Agent Harness

Job description

SOLVING SELF-IMPROVING SUPERINTELLIGENCE The human brain is a sponge. Today’s AI brains are brittle and rigid. At Letta, we’re building self-improving artificial intelligence: creating agents that continually learn from experience and adapt over time. Founded by the creators of MemGPT from UC Berkeley’s Sky Computing Lab (the birthplace of Spark and Ray). Backed by Jeff Dean, Clem Delangue, and pioneers across AI infrastructure. Our agents already power production systems at companies like 11x https://www.letta.com/case-studies/11x and Bilt Rewards https://www.letta.com/case-studies/bilt, learning and improving every day. We’re assembling a world-class team of researchers and engineers to solve AI’s hardest problem: making machines that can reason, remember, and learn the way humans do. Note that this role is in-person (no hybrid), 5 days a week in downtown San Francisco. We are building the developer stack for agents that can run in production applications, not just demo notebooks. As a Software Engineer, you will bridge the gap bleeding-edge agent systems and production-grade software for running agents in real applications. You will help define developer APIs for agents, and lead development of our company’s OSS stack as well as the hosted service. Responsibilities: - Develop Letta's OSS agents framework and cloud service - Design scaleable & resilient backend services and APIs to support Letta Cloud - Work with researchers and support bleeding-edge agent architectures in Letta Required skills: - Strong proficiency with Python - Strong understanding of how to architect services for security, reliability, and performance - Ability to build scaleable backend services - Strong understanding of SQL databases (Postgres) - Familiarity with tooling across the AI stack, such as inference engines (e.g. vLLM, Ollama), and LLM provider APIs (OpenAI, Anthropic) - Bonus: proficient with TypeScript, React, Tailwind, etc. (the modern stack for web applications) OUR CULTURE SIGNS IT COULD BE A GREAT FIT: - You want to maximize your impact: you want work on a small, incredibly talented team where every individual plays a huge role in the team's success. You wonder what it would have been like to be at OpenAI when it was just a dozen people, or Google when it was just a couple of grad students in a garage. - You’re excited to go head-to-head with tech giants, frontier labs, and other startups that are many times our size in both headcount and funding. - You are fundamentally opposed to closed frontier AI that is controlled by a handful of billionaires and private tech companies. SIGNS IT’S A BAD FIT: - You like stability, and get stressed out when there’s nobody telling you exactly what to do. We look for people that thrive in ambiguity and can intuit the most important problems by talking to customers and dogfooding our product. - You want to work a 9-5, and value clear separation of work from life. The stakes are the highest they've ever been, and the only moat is execution velocity. Operating on a strict 9-5 guarantees failure. - You value titles or want to people-manage. Letta is a flat company where every researcher and engineer is an individual contributor. OUR INTERVIEW PROCESS: - Initial screen (30 min) - Technical screen (1-1.5 hours) - Paid in-person work trial (2 days onsite in SF)