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

# Codex

> How to configure Codex CLI to use ZnapAI.

## Overview

Codex CLI is OpenAI's terminal-based coding agent. It can be configured to use Znap AI through an OpenAI-compatible endpoint.

## Step 1: Install Codex CLI

Install globally using npm:

```bash theme={null}
npm install -g @openai/codex
```

Verify installation:

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

## Step 2: Log Out of Existing OpenAI Sessions

If you have previously logged into Codex using a ChatGPT account, clear the existing authentication first:

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

This ensures Codex uses your custom configuration instead of stored OpenAI credentials.

## Step 3: Configure Codex

Open the config file:

```text theme={null}
C:\Users\<your-username>\.codex\config.toml
```

Add the following:

```toml theme={null}
openai_base_url = "https://api.znapai.com/v1"
model = "gpt-5.3-codex"
model_reasoning_effort = "high"
```

Save the file.

## Step 4: Start Codex

Launch the CLI:

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

<Frame>
  <img src="https://mintcdn.com/znapai/bcR0dYQVIgXQaCFj/images/integrations/codex-terminal.png?fit=max&auto=format&n=bcR0dYQVIgXQaCFj&q=85&s=faf947aca5617855d72376a7d1de626c" alt="Codex Terminal" width="813" height="374" data-path="images/integrations/codex-terminal.png" />
</Frame>

When prompted, select:

```text theme={null}
Provide your own API key
```

Paste your Znap AI API key.

## Step 5: Verify Setup

Run a simple prompt:

```text theme={null}
What is 2 + 2?
```

If Codex responds successfully, the configuration is working.

## Changing Models

Update the `model` field in your configuration file:

```text theme={null}
C:\Users\<your-username>\.codex\config.toml
```

Example:

```toml theme={null}
model = "gpt-5.3-codex"
```

Restart Codex after making changes.

## Notes

* Codex uses the OpenAI Responses API internally.
* Znap AI successfully routes Codex requests through its OpenAI-compatible endpoint.
* At the time of writing, GPT-based models have been verified to work reliably with Codex.
* If you encounter errors such as:
  ```text theme={null}
  stream disconnected before completion
  ```
  try switching to a GPT-based model and restart Codex.

## Troubleshooting

### Requests Still Going to OpenAI

Run:

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

Then restart Codex and re-enter your Znap AI API key.

### Invalid API Key Error

Ensure you are using your Znap AI API key and not an OpenAI API key.

### Stream Disconnected Before Completion

This usually indicates a compatibility issue between the selected model and Codex's Responses API requirements.

Switch back to a GPT-based model:

```toml theme={null}
model = "gpt-5.3-codex"
```

and restart Codex.

## Current Recommendation

For Codex CLI, the most reliable configuration currently tested is:

```toml theme={null}
openai_base_url = "https://api.znapai.com/v1"
model = "gpt-5.3-codex"
model_reasoning_effort = "high"
```

This configuration has been verified to work successfully with Znap AI.