OpenAI Codex
Also known as: Codex, Codex CLI, Codex IDE extension
OpenAI Codex is OpenAI's coding agent. The open-source Codex CLI (Apache-2.0) runs locally in your terminal on macOS, Linux, and Windows, and Codex is also available as an IDE extension (VS Code, Cursor, and Devin Desktop (formerly Windsurf)), in the desktop app, and in the cloud at chatgpt.com/codex, with GitHub and Slack integrations. By default it can read files, make edits, and run commands inside a sandboxed workspace, asking for approval before editing outside it or accessing the network.
Agent Information
- Provider
- OpenAI
- Supported IDEs
- Terminal / CLI, VSCode, Cursor, Devin Desktop (formerly Windsurf), Desktop app, Web
Feature Support Matrix
| Feature | Support Level | Details |
|---|---|---|
| Execution | ||
| Automatic Context Awareness | ✅ Full Support | The IDE extension starts from what you already have open: it references open files, selected code, and recent chats from... |
| Filesystem Access | ✅ Full Support | In the default workspace-write sandbox, Codex can read files, make edits, and run commands in the workspace; it requires... |
| MCP Server Support | ✅ Full Support | The ChatGPT desktop app, Codex CLI, and IDE extension support MCP servers and share MCP configuration for the same Codex... |
| Editor Integration | ||
| Broad IDE Integration | ⚠️ Partial | The Codex IDE extension supports VS Code and VS Code-based editors such as Cursor and Devin Desktop (formerly Windsurf).... |
| Model Support | ||
| Latest Claude Model Support | ❓ Unknown | Not documented: the full official documentation (https://learn.chatgpt.com/llms-full.txt) was searched on 2026-09-30 wit... |
| Context Window Management | ❓ Unknown | Not documented: the full official documentation (https://learn.chatgpt.com/llms-full.txt) was searched on 2026-09-30 wit... |
| Debugging | ||
| Console Error Integration | ✅ Full Support | In the ChatGPT desktop app, Developer mode gives the agent controlled Chrome DevTools Protocol access to inspect console... |
| Interactive Element Selection | ✅ Full Support | In the built-in browser, Annotate mode lets you click an element or drag to select an area, leave a comment, and ask the... |
| Live Web Preview | ✅ Full Support | The ChatGPT desktop app has a built-in browser: start your dev server, open the local route, and review the rendered pag... |
| Configuration | ||
| Dedicated Instruction File | ✅ Full Support | Codex reads AGENTS.md (or AGENTS.override.md) files for persistent instructions. |
| Fine-Grained Instruction Control | ⚠️ Partial | AGENTS.md files in nested directories are concatenated from the Git root down, so files closer to the working directory ... |
| Supports Scoped Instructions | ✅ Full Support | Instructions are layered: a global file in ~/.codex, then project files from the Git root down to the working directory. |
| Planning | ||
| Planner Strategy | ✅ Full Support | The /plan command switches the chat into plan mode so Codex proposes an execution plan before implementation starts. |
Frequently Asked Questions
Codex is included in the ChatGPT Plus, Pro, Business, Edu, and Enterprise plans. Free and Go plans can also use Codex in the ChatGPT desktop app with GPT-6 Luna, where available.
Install it with npm (npm install -g @openai/codex), Homebrew (brew install --cask codex), the install scripts from chatgpt.com, or a binary download from GitHub. It runs on macOS (Apple Silicon and x86_64), Linux (x86_64 and arm64), and Windows.
Since late September 2026, OpenAI has been rolling out GPT-6 Sol and GPT-6 Luna in Codex, at lower token prices than their GPT-5.6 predecessors. For complex coding and professional work, OpenAI recommends GPT-6.1 Sol. The documentation does not name a single default model.
By default Codex uses the workspace-write sandbox: it can read files, make edits, and run commands in the active workspace, but needs approval to edit outside it or to access the network, and network access is off by default. A read-only mode is also available.