Codex

What It Does

OpenAI's cloud-based agentic coding environment. Runs tasks in isolated sandboxes, handles multi-file changes, executes tests, and creates pull requests - all asynchronously in the cloud.

Available On

• ChatGPT - Integrated into ChatGPT Pro and Team plans
• API - Available via OpenAI Codex API
• GitHub - Direct integration for PRs and code review

Key Features

• Cloud sandboxes - Each task runs in an isolated environment with your repo cloned
• Parallel execution - Queue multiple tasks and they run concurrently
• Test-driven - Writes code, runs your test suite, iterates until tests pass
• Pull requests - Outputs changes as ready-to-review PRs
• AGENTS.md - Project-level instructions file for custom coding standards
• Full repo context - Clones and indexes your entire repository

Who It's For

Teams who want to offload well-defined coding tasks. Best for issues that can be described clearly and verified with tests.

Bottom Line: Different philosophy than Claude Code - async cloud tasks vs interactive terminal sessions. Great for parallelizing routine work across your backlog.