OpenAI Codex CLI is an open-source, terminal-native coding agent built in Rust by OpenAI.¹⁾ It reads, edits, and executes code locally with optional cloud-sandboxed execution, featuring Git integration, configurable approval policies, and support for multiple execution modes.

ai_agent cli coding openai rust terminal open_source

Codex CLI brings OpenAI's coding capabilities directly into the terminal. Built in Rust for performance, it operates as an autonomous agent that analyzes repositories, proposes code changes, executes them with configurable approval, and iterates based on feedback.²⁾ It supports local, worktree (isolated Git branch), and cloud execution modes, making it suitable for everything from quick edits to complex multi-file refactors.

• Terminal-Native – Runs directly in your shell; no browser or IDE required
• Three Execution Modes – Local (current directory), Worktree (isolated Git branch), Cloud (remote sandboxed)
• Built-in Git Tools – Diff pane with inline comments, staging/reverting chunks, code review before commits
• Integrated Terminal – Toggle via Cmd+J; Codex reads output for validation
• Approval Policies – untrusted (always prompt), on-failure, on-request, never (full auto)
• TOML Configuration – Profiles, multiple precedence levels (CLI args > profiles > config.toml > defaults)
• MCP Support – Manage external tool servers (add/list/get/remove/login/logout)
• GitHub Actions – openai/codex-action@v1 for CI/CD integration³⁾
• Enterprise Features – Enhanced capabilities for business use (v0.116.0+)

Codex CLI follows an agent loop: analyze the repository, generate changes, execute with approval, and iterate on feedback. The Rust core ensures low latency and efficient resource usage.⁴⁾

• Default – gpt-5-codex
• Switchable – GPT-5.4, GPT-5.3-Codex, GPT-4o, o3, and more via /model command
• Custom Providers – Any OpenAI-compatible API (Azure, Bedrock, custom endpoints)

Model configuration via TOML:

model = "gpt-5-codex"
model_provider = "openai-chat-completions"
 
[model_providers.openai-chat-completions]
base_url = "https://api.openai.com/v1"
env_key = "OPENAI_API_KEY"
wire_api = "chat"

# Via npm
npm i -g @openai/codex
 
# Via Homebrew
brew install codex
 
# From source (Rust)
cargo install codex
 
# First run prompts for authentication:
# - ChatGPT account (Plus/Pro/Business/Enterprise)
# - or API key
codex

# Start interactive session
codex
 
# Switch models during session
/model gpt-5.4
 
# MCP server management
codex mcp add docs -- docs-server --port 4000
codex mcp list --json
codex mcp get docs
codex mcp remove docs
 
# Use profiles
codex --profile enterprise --model o3
 
# GitHub Actions integration
# Uses openai/codex-action@v1 in workflow YAML

• Codex CLI on GitHub
• Official Documentation
• Configuration Reference
• GitHub Integration

• GitHub Copilot – GitHub Copilot ecosystem with agent mode
• Plandex – Open-source AI coding agent for large projects
• Claude Code – Anthropic Claude Code CLI agent
• Warp Terminal – Warp agentic development environment