AI Systems Engineer, Codex Agents
OpenAI · San Francisco, CA · Applied AI
About this role
OpenAI is hiring a senior-level AI Infrastructure Engineer in the machine learning function based in San Francisco, CA. The posting calls out experience with Python, Rust, LLMs, Distributed Systems. Compensation is listed at $230,000–$385,000 per year.
- Role
- AI Infrastructure Engineer
- Function
- machine learning
- Level
- senior
- Track
- Individual contributor
- Employment
- Full-time
- Location
- San Francisco, CA
- Department
- Applied AI
- Posted
- May 15, 2026
More roles at OpenAI
Job description
from OpenAI careersAI Systems Engineer - Codex Core Agents
About The Team
The Codex Core Agents team builds the agent harness that turns model capability into real-world action. We own the systems around the model: prompting and interpreting model outputs, executing actions safely in real environments, and feeding production experience back into better models and better agent behavior.
This team sits close to research and works across the stack: harness, model interaction, inference, sandboxed execution, orchestration, evals, production reliability, and the performance envelope around tokens, latency, cost, capacity, and quality. The harness is open source and increasingly part of how models are trained and evaluated, making this one of the highest-leverage layers in Codex.
About The Role
We’re looking for engineers to build the AI systems that make Codex agents dependable in production. The ideal candidate is an agent-systems builder: hands-on across low-level systems and ML workflows, able to debug Codex behavior end to end across the harness, model behavior, inference/runtime stack, GPU fleet, and product surface.
You’ll work with research, infrastructure, and product to design agent harness capabilities, run experiments and ablations across the model + system prompt + harness stack, build frameworks for assessing production agent performance, and turn messy failures into durable improvements.