Staff AI Systems Engineer - RL Environments & Tooling

Jack & Jill; San Francisco (CA); On-site; USD 180,000 - 240,000; Full time

Benefits offered by this job

Equity

Job summary

Jack & Jill in San Francisco builds RL environments and robust backend services to stress-test frontier AI models. You will collaborate with Applied Researchers to translate designs into production-grade software and evaluation systems.

The role demands hands-on work with React/TypeScript and Python or Go, plus LLM APIs, agentic loops, and tool calling in a fast-moving startup. You’ll contribute to scalable systems, tooling, and infrastructure while shaping research-to-production workflows.

Qualifications

• 4+ years of production software experience with a full-stack React/TypeScript and Python or Go stack.
• Hands-on experience with LLM APIs, agentic loops, and owning complex systems in a fast-paced startup environment.
• Strong emphasis on reliability, scalability, and high-velocity delivery.

Responsibilities

• Develop complex RL environments, robust backend services, and tooling to stress-test frontier AI models.
• Partner with Applied Researchers to translate environment designs into production-grade software and evaluation systems.

Skills

React

TypeScript

Python

FastAPI

Go

Reinforcement Learning

LLM APIs

Full-stack Development

Backend Services

Agentic Loops

Tool Calling

AI Safety

Infrastructure Development

Simulation Research

Evaluation Systems

System Architecture

Tools

Production-grade tooling

Job description

Jack & Jill in San Francisco builds RL environments and robust backend services to stress-test frontier AI models. You will collaborate with Applied Researchers to translate designs into production-grade software and evaluation systems.

The role demands hands-on work with React/TypeScript and Python or Go, plus LLM APIs, agentic loops, and tool calling in a fast-moving startup. You’ll contribute to scalable systems, tooling, and infrastructure while shaping research-to-production workflows.