Software Engineer, API Frontiers

API Frontiers turns OpenAI's frontier models into production APIs that developers can use to build reliable products and agents. We own the core path connecting models to developers through the Responses API, with a focus on safety, reliability, and speed. Working closely with Research, Safety, Codex, and other API teams, we bring new model capabilities into production and improve them through developer feedback.

We are looking for a backend software engineer to build and operate the services behind the Responses API. You will shape API behavior, bring new capabilities from research into production, and make long-running agent workflows dependable and fast. The work combines distributed systems engineering with product judgment: designing useful developer interfaces, managing staged rollouts, and following production issues through to durable fixes.

In this role, you will:

• Design, build, and operate APIs and backend services that bring frontier model capabilities to developers.
• Partner with Research, Safety, Codex, and API teams to define API behavior and deliver safe, staged launches.
• Build API capabilities for agent workflows, including task delegation, context sharing, and parallel execution.
• Strengthen long-running request reliability across timeouts, cancellation, streaming, and background execution.
• Improve request-processing performance and tail latency through profiling, efficient systems code, and persistent connections.
• Turn developer feedback and production failures into better observability, diagnostics, and lasting product improvements.

Your background might look something like: 5+ years of experience building and operating backend services or developer-facing APIs in production. Strong software engineering fundamentals, with practical knowledge of distributed systems, concurrency, and asynchronous execution. Ability to diagnose production failures and performance bottlenecks using observability data and profiling. Product