> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nano-gpt.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Codex CLI

> Using OpenAI Codex CLI with NanoGPT

# Codex CLI

> Use OpenAI's Codex CLI with NanoGPT to access GPT-5.2, Claude Opus 4.5, Gemini 3 Flash Preview, and 400+ AI models through a single API key.

<Tip>
  [Get started with NanoGPT](https://nano-gpt.com/api) for pay-as-you-go pricing with no monthly fees. Add credits and start coding immediately.
</Tip>

NanoGPT provides an OpenAI API-compatible endpoint that works seamlessly with Codex CLI. This allows you to:

* Use Codex CLI with your NanoGPT credits
* Access OpenAI models (GPT-5.2 and more) without a separate OpenAI account
* Route to 400+ other models including Claude Opus 4.5, Gemini 3 Flash Preview, and GLM 4.7

## Step 1: Install Codex CLI

<Tabs>
  <Tab title="Recommended Installation Method">
    Prerequisites: [Node.js 22 or newer](https://nodejs.org/en/download/)

    ```bash theme={null}
    # Install Codex CLI
    npm install -g @openai/codex

    # Navigate to your project
    cd your-awesome-project

    # Start Codex
    codex
    ```
  </Tab>

  <Tab title="Cursor Guided Installation Method">
    If you are not familiar with npm but have Cursor, you can enter the command in Cursor, and Cursor will guide you through the installation.

    ```
    https://developers.openai.com/codex/cli/ Help me install Codex CLI
    ```
  </Tab>
</Tabs>

<Note>
  **Note**: If you encounter permission issues during installation, try using `sudo` (macOS/Linux) or running the command prompt as an administrator (Windows) to re-execute the installation command.
</Note>

## Step 2: Configure NanoGPT

<Steps>
  <Step title="Get API Key">
    * Go to [NanoGPT API](https://nano-gpt.com/api)
    * Create an account or log in
    * Copy your API key
  </Step>

  <Step title="Configure Codex">
    Set up Codex using one of the following methods:

    <Tabs>
      <Tab title="One-Click Setup (Mac/Linux)">
        Run this command in your terminal:

        ```bash theme={null}
        curl -O "https://nano-gpt.com/install/codex_nanogpt.sh" && bash ./codex_nanogpt.sh
        ```

        The script will:

        1. Prompt for your API key
        2. Create `~/.codex/config.toml` with NanoGPT configuration
        3. Add `NANOGPT_API_KEY` to your shell profile

        The installer now supports browser-based login. When the script starts, choose:

        1. Browser login (recommended) - it will open a verification URL, wait for approval, and then save your key in `~/.codex/config.toml`.
        2. Paste API key - manual fallback if you prefer.

        If a browser does not open automatically, copy the printed URL into your browser and approve the request.

        For more details on the browser login flow, see [CLI login](https://docs.nano-gpt.com/integrations/cli-login).
      </Tab>

      <Tab title="Manual Configuration (All Platforms)">
        **Step 1**: Create `~/.codex/config.toml`:

        ```toml theme={null}
        model_provider = "nanogpt"
        model = "openai/gpt-5.2"

        [model_providers.nanogpt]
        name = "NanoGPT"
        base_url = "https://nano-gpt.com/api/v1"
        env_key = "NANOGPT_API_KEY"
        wire_api = "responses"
        ```

        Recent Codex CLI versions require `wire_api = "responses"`. Older examples that use `wire_api = "chat"` will fail on current Codex CLI releases.

        **Step 2**: Set your API key as an environment variable:

        **macOS/Linux** (add to `~/.zshrc` or `~/.bashrc`):

        ```bash theme={null}
        export NANOGPT_API_KEY="your_nanogpt_api_key"
        ```

        **Windows Cmd**:

        ```cmd theme={null}
        setx NANOGPT_API_KEY your_nanogpt_api_key
        ```

        **Windows PowerShell**:

        ```powershell theme={null}
        [System.Environment]::SetEnvironmentVariable('NANOGPT_API_KEY', 'your_nanogpt_api_key', 'User')
        ```

        Replace `your_nanogpt_api_key` with your actual API key. Open a new terminal for changes to take effect.
      </Tab>

      <Tab title="Environment Variables Only (Quick)">
        If you just want to override the default OpenAI endpoint without a config file:

        ```bash theme={null}
        export OPENAI_BASE_URL="https://nano-gpt.com/api/v1"
        export OPENAI_API_KEY="your_nanogpt_api_key"
        ```

        This method works but does not persist across terminal sessions unless added to your shell profile.
      </Tab>
    </Tabs>
  </Step>
</Steps>

## Step 3: Start Using Codex

Once configured, start Codex in your terminal:

```bash theme={null}
codex
```

Or specify a model directly:

```bash theme={null}
codex --model openai/gpt-5.2
```

***

## FAQ

### What Models Can I Use?

NanoGPT supports 400+ models. Popular choices for Codex:

| Use Case     | Recommended Model               | Config                                    |
| ------------ | ------------------------------- | ----------------------------------------- |
| Best overall | `openai/gpt-5.2`                | `model = "openai/gpt-5.2"`                |
| Best Claude  | `anthropic/claude-opus-4.5`     | `model = "anthropic/claude-opus-4.5"`     |
| Fast/cheap   | `google/gemini-3-flash-preview` | `model = "google/gemini-3-flash-preview"` |
| Long context | `google/gemini-3-pro-preview`   | `model = "google/gemini-3-pro-preview"`   |
| Open model   | `zai-org/glm-4.7`               | `model = "zai-org/glm-4.7"`               |

List available models with `GET https://nano-gpt.com/api/v1/models`.

### How Do I Change Models?

**Option 1**: Edit `~/.codex/config.toml`:

```toml theme={null}
model = "openai/gpt-5.2"
```

**Option 2**: Use CLI flag:

```bash theme={null}
codex --model openai/gpt-5.2
```

### Configuration Not Working?

1. **Check your API key**: Ensure `NANOGPT_API_KEY` is set
   ```bash theme={null}
   echo $NANOGPT_API_KEY
   ```

2. **Verify config file**: Check `~/.codex/config.toml` exists and has valid TOML syntax

3. **Open a new terminal**: Environment variable changes require a new shell session

4. **Reset configuration**: Delete `~/.codex/config.toml` and run the setup script again

### How Is This Different From Using OpenAI Directly?

| Feature     | OpenAI Direct                       | NanoGPT                            |
| ----------- | ----------------------------------- | ---------------------------------- |
| Pricing     | Monthly subscription or API credits | Pay-as-you-go, no minimums         |
| Models      | OpenAI only                         | OpenAI + Claude + 400 other models |
| Billing     | Separate OpenAI account             | Single NanoGPT balance             |
| Rate limits | OpenAI limits                       | NanoGPT limits                     |

### Can I Use Both Claude Code and Codex?

Yes. Both can be configured to use NanoGPT simultaneously:

* **Claude Code**: Uses `~/.claude/settings.json` with Anthropic API format
* **Codex CLI**: Uses `~/.codex/config.toml` with OpenAI API format

Both tools share the same NanoGPT credit balance.

### Need Help?

* Check your balance at [nano-gpt.com/balance](https://nano-gpt.com/balance)
* View API usage at [nano-gpt.com/usage](https://nano-gpt.com/usage)
* Create or manage API keys at [nano-gpt.com/api](https://nano-gpt.com/api)
* Contact support via the chat widget on [nano-gpt.com](https://nano-gpt.com)