npm i -g @openai/codex
or brew install --cask codex

Codex CLI is a coding agent from OpenAI that runs locally on your computer.

If you want Codex in your code editor (VS Code, Cursor, Windsurf), install in your IDE.
If you are looking for the cloud-based agent from OpenAI, Codex Web, go to chatgpt.com/codex.

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RLM Runtime (Large Context Processing)

RLM (Recursive Language Model) is an embedded Python runtime that enables agents to efficiently process large codebases and documents. Instead of loading entire files into context, RLM provides tools for structured navigation and extraction.

Key Features:

• Load directories up to 100MB with automatic file filtering (binary, oversized, gitignored)
• Python builtins: peek_doc(), find(), search(), list_docs(), stats()
• Hierarchical routing via AGENTS.md files for codebase navigation
• Sub-agent spawning with llm_query() for complex analysis
• Coverage tracking and broken link detection for routing validation

Documentation:

• RLM Runtime Spec — Full specification and tool reference
• RLM Installation Guide — Prerequisites and build instructions (requires Python 3.11+)

Quick Start:

Add to your AGENTS.md file something like:

Use RLM for tasks that require reading and analyzing large context.

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Quickstart

Installing and running Codex CLI

Install globally with your preferred package manager:

# Install using npm
npm install -g @openai/codex

# Install using Homebrew
brew install --cask codex

Then simply run codex to get started.

You can also go to the latest GitHub Release and download the appropriate binary for your platform.

Each GitHub Release contains many executables, but in practice, you likely want one of these:

• macOS
  • Apple Silicon/arm64: codex-aarch64-apple-darwin.tar.gz
  • x86_64 (older Mac hardware): codex-x86_64-apple-darwin.tar.gz
• Linux
  • x86_64: codex-x86_64-unknown-linux-musl.tar.gz
  • arm64: codex-aarch64-unknown-linux-musl.tar.gz

Each archive contains a single entry with the platform baked into the name (e.g., codex-x86_64-unknown-linux-musl), so you likely want to rename it to codex after extracting it.

Using Codex with your ChatGPT plan

Run codex and select Sign in with ChatGPT. We recommend signing into your ChatGPT account to use Codex as part of your Plus, Pro, Team, Edu, or Enterprise plan. Learn more about what's included in your ChatGPT plan.

You can also use Codex with an API key, but this requires additional setup.

Docs

• Codex Documentation
• Contributing
• Installing & building
• Open source fund

This repository is licensed under the Apache-2.0 License.