Judgment Labs — Full-Stack Engineer

• →Build interfaces that make large-scale, parallel agent investigations legible — turning thousands of production traces and a wide range of failure signals into a single actionable answer.
• →Build the platform for verifying agent changes: simulated environments for stateful evals, trajectory replay, and monitors for unintended behavior.
• →Make long, multi-step reasoning trajectories understandable in minutes.
• →Own the improvement loop end to end, turning production data into datasets, judges, and regression checks.
• →Build and maintain the SDK and a terminal-first developer experience.
• →Own core platform infrastructure: workspaces, permissions, billing, usage, and limits.

Tech stack: Full-stack (data layer through UI), SDK development, terminal-first tooling, agent/LLM infrastructure.

• 3–7 years of full-stack engineering experience, comfortable owning systems from the data layer through the UI
• Hands-on experience building with LLMs or AI agents (or a clear, demonstrated drive to ramp fast)
• A track record of shipping and scaling production systems end to end
• Comfortable working directly with customers to understand needs and solve real problems (~30% of the role)
• Strong problem-solving in fast-moving, ambiguous environments
• Clear, direct, persuasive communication across technical and non-technical audiences
• Based in San Francisco or open to relocating; in-office 5 days a week

• Prior work on evals, observability, or agent behavior-monitoring products
• Strong engineering pedigree from a respected product company; top-tier infrastructure experience is a bonus
• Prior forward-deployed or solutions engineering experience
• Early-stage / 0-to-1 startup experience as an early hire
• A technical edge beyond delivery — coding competitions, research, or similar
• Founder background or a clear founder-to-be trajectory
• Full-stack comfort with real backend and infrastructure depth

• Location — San Francisco, CA
• Work policy — On-site, 5 days/week; relocation supported
• Compensation — $200,000–$300,000 + equity
• Visa sponsorship — Considered case-by-case for exceptional candidates; primary scope is candidates who don't require sponsorship
• Employment type — Full-time