MultiCodex

MultiCodex is a small Windows desktop app for launching multiple native Codex desktop windows.

Open MultiCodex, click the large plus button, and a new Codex desktop app process starts with its own isolated profile. Click plus again to start another Codex window without stopping the ones already running. Use the X button in the list to close one launched Codex instance.

Download And Install

Download the latest Windows installer from the GitHub Releases page:

https://github.com/imthegoodboy/MultiApp/releases

Run the latest MultiCodex-*-Setup.exe file and follow the setup wizard. The installer creates Start Menu and desktop shortcuts with the MultiCodex icon.

Windows may show a SmartScreen warning because this first release is not code-signed. Choose the standard "More info" and "Run anyway" flow only if you trust this repository and release.

Requirements

MultiCodex launches the native Codex desktop app. Install Codex first, then install MultiCodex.

On Windows, MultiCodex automatically looks for:

1. MULTICODEX_CODEX_COMMAND
2. The installed Windows packaged app OpenAI.Codex
3. Common Codex.exe install paths
4. codex from the system path

If Codex is installed somewhere custom, set this before starting MultiCodex:

$env:MULTICODEX_CODEX_COMMAND = "C:\Path\To\Codex.exe"

How It Works

Each Codex launch is separate:

• every plus click creates a new Codex process
• every instance gets a unique profile directory
• every desktop executable launch gets a unique --user-data-dir=<profile>\electron-user-data
• existing Codex windows keep running when another one is launched
• closing MultiCodex does not close already-launched Codex windows
• the row X button closes only that one launched Codex instance
• the installed app, window, taskbar, installer, and shortcuts use the MultiCodex icon

Each launched process receives these environment variables:

• CODEX_HOME
• OPENAI_CODEX_HOME
• ELECTRON_USER_DATA_DIR
• MULTICODEX_INSTANCE_ID
• MULTICODEX_PROFILE_PATH
• MULTICODEX_WORKSPACE_PATH

Development

Install dependencies:

npm install

Run the Electron app:

npm run dev

Build and test:

npm run typecheck
npm test
npm run test:e2e
npm run build

Build the Windows installer:

npm run package

The installer is written to the release directory.

For test automation only, set MULTICODEX_KILL_CHILDREN_ON_EXIT=1 to terminate launched child processes when the launcher exits.