OpenAI Codex Integration

OpenAI Codex CLI is an open-source coding agent that runs in your terminal. It can write and edit code, run commands, and work through multi-step tasks using large language models with full sandbox safety.

Codex CLI supports custom OpenAI-compatible endpoints via environment variables.

Prerequisites

An LLM API account with an API key
OpenAI Codex installed or accessible

Setup

Get Your LLM API Key

Log in to your LLM API dashboard
Click Create Key to Start
Copy your new API key immediately — it will only be shown once
Store the key securely (e.g., in a password manager or .env file)

LLM API is an OpenAI-compatible gateway that gives you access to dozens of AI models through a single API key and endpoint.

Configure LLM API in Codex CLI

Set environment variables before launching Codex:

export OPENAI_API_KEY="your-llm-api-key-here"
export OPENAI_BASE_URL="https://api.llmapi.ai/v1"

Launch Codex:

codex

All AI requests will now go through LLM API.

Test the Integration

Verify that OpenAI Codex can successfully communicate with LLM API by sending a test request. All requests will now be routed through LLM API.

OPENAI_BASE_URL overrides the default endpoint. Codex CLI will use LLM API for all model requests.

Benefits of Using LLM API with OpenAI Codex

Multi-Provider Access: Use models from OpenAI, Anthropic, Google, and more through a single API
Cost Control: Track and limit your AI spending with detailed usage analytics
Unified Billing: One account for all providers instead of managing multiple API keys
Caching: Reduce costs with response caching for repeated requests

View all available models on the models page.