Codex (ChatGPT) Integration

Claude Code Router can use a ChatGPT/Codex subscription to route Claude Code requests through OpenAI's models. The Codex backend powers OpenAI's ChatGPT product and this integration lets you leverage that subscription with Claude Code.

Authentication uses OpenAI OAuth — a ChatGPT Plus or Pro subscription is required.

How It Works

1. ccr codex-auth prints an authorization URL and starts a local callback server on port 1455
2. You open the URL in your browser and sign into your OpenAI / ChatGPT account
3. OpenAI redirects to http://localhost:1455/auth/callback, where the CCR server exchanges the authorization code for tokens (PKCE flow)
4. Tokens are saved to ~/.claude-code-router/codex_auth.json
5. You return to the terminal and press Enter — the CLI confirms the tokens were saved
6. The codex transformer reads the access token and uses it to authenticate API requests
7. When the token nears expiry, it's refreshed automatically using the refresh token

Prerequisites

• A ChatGPT Plus or Pro subscription
• Claude Code Router running (Docker Compose or local)

Setup

1. Authenticate

Run the OAuth flow:

ccr codex-auth

The CLI prints an authorization URL. Open it in your browser, sign in with your OpenAI / ChatGPT account, and authorize the application. After the browser shows "Authentication Successful", return to your terminal and press Enter. The tokens are saved automatically.

2. Configure Provider

Add the Codex provider to your ~/.claude-code-router/config.json:

{
  "Providers": [
    {
      "name": "codex",
      "baseUrl": "https://chatgpt.com/backend-api/codex",
      "apiKey": "oauth_dummy_key",
      "models": ["gpt-5", "gpt-5-high", "gpt-5-mini"],
      "transformer": {
        "use": ["codex"]
      }
    }
  ],
  "Router": {
    "default": "codex,gpt-5"
  }
}

3. Restart

docker compose restart ccr

Features

• SSE streaming — Full streaming support for real-time responses
• Reasoning/thinking content — Supports models with reasoning capabilities
• Tool calls — Function calling with multiple tools
• Web search — Built-in web search via { type: "web_search" }
• Image handling — Vision support for image inputs

Usage

Use Codex as your default model or route specific scenarios:

{
  "Router": {
    "default": "codex,gpt-5",
    "webSearch": "codex,gpt-5-high",
    "think": "codex,gpt-5-high",
    "background": "codex,gpt-5-mini"
  }
}

Model Reference

Model	Description
gpt-5	Standard GPT-5 model
gpt-5-high	High-performance variant (reasoning tasks)
gpt-5-mini	Lightweight variant (background tasks)

Troubleshooting

Token expired or invalid: Re-run ccr codex-auth to refresh the token.

Provider not found: Ensure the provider name in your config matches body.model (e.g., codex,gpt-5).