Backend API Engineer — Frontier Models

OpenAI; United States; Remote; USD 150,000 - 230,000; Full time

Job summary

OpenAI is seeking 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 ensure durable and fast long-running agent workflows.

Responsibilities include designing and operating APIs, collaborating with Research, Safety, Codex, and API teams, and improving diagnostics and performance through observability and profiling.

Qualifications

• 5+ years of experience building and operating backend services or developer-facing APIs in production.
• Strong software engineering fundamentals with distributed systems, concurrency, and asynchronous execution.

Responsibilities

• 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.

Skills

Backend development

Distributed systems

APIs

Observability

Profiling

Concurrency

Async execution

Job description

OpenAI is seeking 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 ensure durable and fast long-running agent workflows.

Responsibilities include designing and operating APIs, collaborating with Research, Safety, Codex, and API teams, and improving diagnostics and performance through observability and profiling.