Harness engineering: leveraging Codex in an agent-first world

Sea's View on the Future of Agentic Software Development with Codex

Sea Limited's CPO explains why the company is deploying Codex across engineering teams to accelerate AI-native software development in Asia.

Codex for every role, tool, and workflow

Discover new Codex plugins, sites, and annotations that help analysts, marketers, designers, investors, and other teams get more done with AI.

Addendum to o3 and o4-mini system card: Codex

Codex is a cloud-based coding agent. Codex is powered by codex-1, a version of OpenAI o3 optimized for software engineering.

Unrolling the Codex agent loop

A technical deep dive into the Codex agent loop, explaining how Codex CLI orchestrates models, tools, prompts, and performance using the Responses API.

Introducing AgentKit, new Evals, and RFT for agents

Today, we’re releasing new tools to help developers go from prototype to production faster: AgentKit, expanded evals capabilities, and reinforcement fine-tuning for agents.

Unlocking the Codex harness: how we built the App Server

Learn how to embed the Codex agent using the Codex App Server, a bidirectional JSON-RPC API powering streaming progress, tool use, approvals, and diffs.

Codex is becoming a productivity tool for everyone

The Next Era of Knowledge Work report explores how Codex is transforming productivity through AI-powered research, data analysis, workflow automation, and content creation.

How Codex became a collaborator for OpenAI’s creative team

How OpenAI’s creative team uses Codex to build custom creative tools, accelerate ideation, and prototype faster with context-aware AI.

Building more with GPT-5.1-Codex-Max

Introducing GPT-5. 1-Codex-Max, a faster, more intelligent agentic coding model for Codex.

New tools for building agents

Building self-improving tax agents with Codex

See how OpenAI, Thrive, and Crete built a self-improving tax agent with Codex, automating filings, improving accuracy, and accelerating workflows.

Introducing Codex