# Prerequisites for Using the Codex Plugin: Complete Setup Guide > Learn the essential prerequisites for using the Codex plugin including OpenAI credentials Nodejs and Codex CLI installation for a seamless setup. - Repository: [OpenAI/codex-plugin-cc](https://github.com/openai/codex-plugin-cc) - Tags: how-to-guide - Published: 2026-07-03 --- **To use the Codex plugin for Claude Code, you need a valid OpenAI credential (ChatGPT subscription or API key), Node.js 18.18 or higher, and the Codex CLI installed on your system.** The openai/codex-plugin-cc repository provides a thin wrapper that integrates OpenAI's Codex CLI into Claude Code. Before executing slash commands like `/codex:review`, you must satisfy three core dependencies that bridge the gap between the Claude environment and OpenAI's code generation services. ## Core Prerequisites ### Valid OpenAI Credentials The plugin forwards all usage to your Codex limits, requiring either a **ChatGPT subscription** (including the free tier) or an **OpenAI API key**. According to the repository's [`README.md`](https://github.com/openai/codex-plugin-cc/blob/main/README.md), these credentials authenticate requests to the Codex app-server. The plugin does not manage billing or quota; it simply passes through your existing OpenAI authentication state. ### Node.js 18.18 or Higher The plugin is built with modern JavaScript/TypeScript and specifically requires **Node.js version 18.18 or greater**. This requirement is declared in the project's [`package.json`](https://github.com/openai/codex-plugin-cc/blob/main/package.json) and enforced because the plugin relies on Node.js features introduced in that version. Attempting to run the plugin on older Node.js versions will result in compatibility errors. ### Codex CLI Binary Unlike self-contained plugins, this integration calls the external `codex` binary from your environment. The plugin does not ship its own runtime; instead, it loads the global `codex` command and reuses your existing configuration files (`~/.codex/config.toml` or [`.codex/config.toml`](https://github.com/openai/codex-plugin-cc/blob/main/.codex/config.toml) in the repo). If the binary is missing, the `/codex:setup` command will detect this and offer to install it automatically. ## Architecture Overview Understanding the data flow clarifies why these prerequisites are mandatory: **Claude Code → Codex plugin → Codex CLI → Codex app-server** When you invoke `/codex:review`, the plugin constructs a command in `plugins/codex/scripts/lib/codex.mjs` and forwards the request to the local Codex app-server. Because the plugin acts as a passthrough layer, it depends entirely on the external CLI for actual code analysis. ## Installation and Verification Follow these steps to satisfy all prerequisites: ```bash # Install the plugin (requires Node ≥ 18.18) /plugin marketplace add openai/codex-plugin-cc /plugin install codex@openai-codex /reload-plugins ``` ```bash # Verify setup and auto-install CLI if missing /codex:setup ``` If you prefer manual installation or the auto-install fails: ```bash # Install Codex CLI globally npm install -g @openai/codex # Authenticate (required if using API key only) !codex login ``` Running `/codex:setup` after these steps validates that all components are present and properly configured. ## Key Integration Files The following files enforce the prerequisite checks: - **[`README.md`](https://github.com/openai/codex-plugin-cc/blob/main/README.md)** – Documents the Node.js version requirements and credential setup. - **`plugins/codex/scripts/lib/codex.mjs`** – The wrapper script that locates and executes the local `codex` binary. - **[`package.json`](https://github.com/openai/codex-plugin-cc/blob/main/package.json)** – Declares the minimum Node.js runtime version. - **[`.claude-plugin/plugin.json`](https://github.com/openai/codex-plugin-cc/blob/main/.claude-plugin/plugin.json)** – Registers the plugin with Claude Code's extension system. ## Summary - **OpenAI credential required** – Either a ChatGPT subscription or API key to access Codex limits. - **Node.js 18.18+ mandatory** – The plugin uses modern JavaScript features unavailable in earlier versions. - **External CLI dependency** – The `codex` binary must be installed separately; the plugin wraps rather than embeds the runtime. - **Auto-installation available** – Running `/codex:setup` can automatically fetch the CLI if missing. - **Configuration reuse** – The plugin reads from `~/.codex/config.toml` and local [`.codex/config.toml`](https://github.com/openai/codex-plugin-cc/blob/main/.codex/config.toml) files. ## Frequently Asked Questions ### Do I need a paid OpenAI subscription to use the Codex plugin? No. According to the openai/codex-plugin-cc source code, you can use either a ChatGPT subscription (including the free tier) or an OpenAI API key. The plugin forwards usage to your existing Codex limits, so billing depends on your OpenAI account type. ### Can I run the Codex plugin without installing the Codex CLI separately? No. The plugin requires the external `codex` binary to be present in your environment. However, if you run `/codex:setup` and the binary is missing, the plugin will offer to install it automatically. Alternatively, you can manually install it via `npm install -g @openai/codex`. ### What happens if my Node.js version is older than 18.18? The plugin will fail to load or execute. The [`package.json`](https://github.com/openai/codex-plugin-cc/blob/main/package.json) in the repository explicitly declares Node.js 18.18 as the minimum requirement, and the code uses features incompatible with earlier versions. You must upgrade Node.js before installing the plugin. ### Where does the Codex plugin store its configuration? The plugin reuses the standard Codex CLI configuration files. It reads from `~/.codex/config.toml` for global settings and [`.codex/config.toml`](https://github.com/openai/codex-plugin-cc/blob/main/.codex/config.toml) within your repository for project-specific overrides. This allows the plugin to maintain authentication state and preferences across sessions.