Mod the Codex desktop app.

Explodex (Extension plugins for Codex) is an extension SDK for OpenAI's Codex desktop app — color-code your projects, keep usage and reset countdowns on screen, set reasoning effort with a keystroke, or build your own by prompting Codex.

Install in 30 seconds · Included plugins · Build a plugin · Docs

npm install -g explodex
explodex

Codex is great but closed. Explodex makes it malleable — so the tweak you keep wishing for is something you can just build. (Used BetterDiscord or Legcord? Same idea, for Codex.)

Explodex ships with a handful of plugins — useful on their own, and good starting points to copy when building your own.

💥 Explodex sidebar item opens a settings page where you can enable/disable plugins and change their options.

Plugin	What it does	Screenshot
Usage and Reset Glance	Keep usage and credit-reset countdowns on screen — no clicking into menus
Project Pins	Pin a thread to its project instead of globally, and keep it at the top
Project Colors	Color-code projects and their threads in the sidebar so you can tell them apart at a glance
Threads in Command Menu	Find any thread from ⌘K — including threads inside collapsed projects, listed first
Effort Shortcuts	Set reasoning effort from the composer — type !m or !xh, stripped on send and restored after
Feature Flags Playground	Toggle Codex's experimental feature flags from Settings — changes persist across restarts

With Explodex you create mods using Codex itself in realtime. Run explodex, and use the bundled skill, describe what you want, and watch it happen in real time. try "it's christmas! add a snowing effect to codex". The plugin-builder skill drives the whole loop (scaffold → SDK hooks → validate → live injection):

• explodex-plugin-builder: canonical workflow; uses an existing Explodex renderer when available and works offline when it is not

Install it with explodex install-skill or npx skills add dan-dr/explodex.

The SDK reference and types keep the agent on stable surfaces; the included plugins double as templates.

my-plugin/
  plugin.json
  index.js

// @ts-check
/// <reference path="../../sdk/explodex-sdk.d.ts" />

(function (global) {
  const Explodex = global.Explodex;
  if (!Explodex?.plugins?.register) return;

  Explodex.plugins.register(
    { id: "hello", name: "Hello", version: "1.0.0" },
    (api) => {
      const render = () =>
        api.mount("aboveComposer", () =>
          api.components.button({
            label: "Insert greeting",
            color: "secondary",
            size: "composerSm",
            onClick: () => api.composer.insertText("Hello! "),
          }),
        );

      render();
      const stop = api.waitFor("aboveComposer", render);
      return () => stop();
    },
  );
})(window);

You'll need macOS, the Codex desktop app at /Applications/Codex.app, and a package manager (Bun, npm, pnpm, or Yarn).

Install globally, then run explodex:

# pick one
npm install -g explodex
pnpm add -g explodex
bun install -g explodex
yarn global add explodex

explodex

You will be prompted to create ~/Applications/Explodex.app, a lightweight launcher: it does not modify, re-sign, or change the bundle ID of Codex. The first interactive run also offers to install the plugin creator skill. Re-run both onboarding checks later with explodex doctor.

See docs/installation.md for commands, launch states, recovery, and logs.

To build plugins, clone the repo and run the dev loop:

git clone https://github.com/dan-dr/explodex.git
cd explodex
bun run dev

bun run dev packages the app, launches Codex with remote debugging, injects the SDK + plugins, and starts Chrome DevTools MCP for live renderer inspection — exactly the loop the agent skills drive. Dev state is isolated under .explodex-user-data/.

Repo layout, the dev loop, validation, and the bun run commands live in docs/development.md.

Explodex creates a thin local launcher (Explodex.app) that starts the unmodified Codex executable with Chrome DevTools Protocol enabled, then injects the npm-packaged SDK and plugins. The SDK (sdk/explodex-sdk.js) provides:

• DOM zones — aboveComposer, sidebar, composerActions, and more
• Components — buttons, panels, toasts styled like Codex
• Bridge — AppServer router and Electron IPC to Codex internals
• Plugin manager — catalog, enable/disable, hot load in dev

Explodex injects locally into Codex's renderer. It never modifies your installed /Applications/Codex.app and runs entirely on your machine. Because it hooks Codex internals, a plugin may need an update when Codex ships a new release — see docs/sdk-fragility.md.

macOS only for now. Not affiliated with, endorsed by, or supported by OpenAI.