How to install a Codex plugin: CLI, app and GitHub repos

Disclosure: I run PickAPlugin, an independent catalog of ChatGPT and Codex plugins. This is adapted from our guide on the same topic.

There are basically three ways a plugin gets onto your machine: the built-in directory, a GitHub repo that ships a marketplace, or a folder you made yourself. Here's each one.

1. From the built-in directory (easiest)

In the Codex app or ChatGPT desktop app, open Plugins, search, open the plugin and hit install. In the CLI, start codex and type /plugins. Plugins in the OpenAI tab are the ones OpenAI curates, so this is the low-risk route.

2. From a GitHub repo

Most community plugins live in a repo that has a .agents/plugins/marketplace.json (or the older .claude-plugin/marketplace.json). You add the repo as a marketplace once, then install by name:

codex plugin marketplace add owner/repo
codex plugin list
codex plugin add plugin-name@marketplace-name

The marketplace name comes from the name field in that repo's marketplace.json, and codex plugin list shows it.

Point it at the repo, not the raw marketplace.json URL. The command clones a git repo, so a raw file link fails with a 404.

3. From a local folder

Put the plugin in ./plugins/my-plugin (repo) or ~/.codex/plugins/my-plugin (personal), then list it in .agents/plugins/marketplace.json with "source": {"source": "local", "path": "./plugins/my-plugin"}. Restart the app and it shows up.

Before you install anything from GitHub

Community plugins can bundle hooks, MCP servers and shell commands. Spend two minutes on the repo: when was the last commit, what does .mcp.json start, are there hooks.

Quick answers

• Where do plugins get installed? Into ~/.codex/plugins/cache/MARKETPLACE/PLUGIN/VERSION/. Local plugins use the version local.
• How do I remove one? codex plugin remove plugin-name@marketplace, or uninstall from the Plugins view in the app.
• Why a 404 on marketplace add? Usually a raw marketplace.json URL. Give it the repo instead.

The full guide, with an install command finder, is at https://pickaplugin.com/guides/install-codex-plugin