OpenAI Codex CLI

Codex CLI is a terminal-based coding agent that combines local execution with cloud AI capabilities. Unlike code generation tools that only produce code snippets, Codex CLI can understand your entire project, execute the code it creates, debug issues, and iterate until solutions work correctly.

How to Access OneRouter

Installation

Install via npm (Recommended)

npm install -g @openai/codex

Install via Homebrew (macOS)

brew install codex

Verify Installation

codex --version

Configuring OneRouter AI Models

Setup Configuration File

Codex CLI uses a TOML configuration file located at:

• macOS/Linux: ~/.codex/config.toml

• Windows: %USERPROFILE%\.codex\config.toml

Basic Configuration Template

model = "gpt-5.1-chat"
model_provider = "onerouter"

[model_providers.onerouter]
name = "OneRouter"
base_url = "https://llm.onerouter.pro/v1"
http_headers = {"Authorization" = "Bearer YOUR_ONEROUTER_API_KEY"}
wire_api = "chat"

Getting Started

Launch Codex CLI

codex

Basic Usage Examples

Code Generation:

> Create a Python class for handling REST API responses with error handling

Project Analysis:

> Review this codebase and suggest improvements for performance

Bug Fixing:

> Fix the authentication error in the login function

Conclusion

Codex CLI with OneRouter AI models provides a powerful, flexible development environment that combines local control with cloud AI capabilities. By choosing the right model for each task and configuring your environment properly, you can significantly accelerate your development workflow while maintaining code quality and security.