OpenAI Codex
Cloud-based autonomous coding agent integrated into ChatGPT, capable of executing multi-step software tasks in sandboxed environments with 3M+ weekly developers.
Overview
OpenAI Codex is a cloud-based autonomous coding agent launched in 2025 that can execute complex software engineering tasks in sandboxed environments. Integrated directly into ChatGPT, it can read codebases, make changes, run tests, and submit pull requests autonomously—serving over 3 million weekly developers.
Architecture
Each Codex session spins up an isolated sandbox with network access to npm, PyPI, and other package registries. It clones your repository, installs dependencies, and executes tasks with full filesystem access. A specialized model called codex-mini is used for file editing operations.
Use Cases
Autonomous feature implementation, bug fixing and debugging, test suite creation, code migration, library upgrades, and project scaffolding.