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

# Codex API key

> Use an OpenAI API key stored securely by Radius.

| Item          | Behavior                                                   |
| ------------- | ---------------------------------------------------------- |
| Use for       | A first-party OpenAI API key                               |
| Configuration | A Radius-owned isolated `CODEX_HOME`                       |
| Credentials   | `OPENAI_API_KEY` for the default OpenAI provider           |
| Isolation     | Your normal Codex login and configuration do not take over |

## How it works

1. Select **API Key** and save your OpenAI key.
2. Radius stores the key in encrypted credential storage.
3. Radius removes ambient OpenAI and Azure credentials from the launched
   process, then supplies the saved key.
4. Codex discovers and runs models with the isolated configuration.

Radius does not send the key to the page renderer or write it into
`config.toml`.

## Advanced Azure setup

You can edit the isolated advanced `config.toml` to define Azure, then save the
Azure key in Radius. Radius supplies the key through the `env_key` named by that
configuration.

For most Azure setups, use [Codex CLI](/docs/agents/codex/cli) instead.