How to build and submit your own ChatGPT plugin extension

Pick one job people already do by hand

The best first plugin does one boring thing well. Think of what people search for or do manually every week: turning a PDF table into a spreadsheet, making an invoice, writing the same client report every Friday.

• It has to do something ChatGPT can’t already do. OpenAI’s guidelines reject plugins that duplicate built-in features.
• No demos or trials. The plugin has to be complete and work reliably.
• Don’t wrap someone else’s API without their permission. An unofficial connector to another company’s service won’t be approved.

Build the engine: an MCP server

A plugin is an MCP server (the tools ChatGPT can call), skills (written instructions), or both. For anything with an extension, you need the server. It has to run at a public HTTPS URL, not on your laptop.

To get a feel for it before writing any code, connect OpenAI’s sample server:

1. In ChatGPT, go to Settings → Security and login and turn on Developer mode.
2. Go to ChatGPT Plugins, hit +, and paste https://tinymcp.dev/api/moldy-aloof-zettabyte/mcp.
3. Install it from your personal plugins, switch the homepage tab from Chat to Work, type @, pick it, and ask it to roll a 20-sided die.

Then swap in your own server. Keep it to a few tools, name each one as a plain verb (get_order_status, not best_tool), and describe exactly what it does.

Add the extension

This is the new part. Extensions are what turn a plugin from a tool ChatGPT calls into an app people see. You declare one with a few lines in OpenAI’s SDK (@openai/mcp-extensions for TypeScript, or the MCP Python SDK). The ones most people will want:

• Sidebar app. Your app gets its own entry in ChatGPT’s sidebar and opens fullscreen. Canva does this.
• Conversation panel. Your app opens beside the chat, so the work and the conversation sit together.
• File viewer or editor. When someone opens a file type you support, it opens in your app. Adobe uses this to edit Photoshop and Acrobat files inside ChatGPT.
• Composer mentions. People can @ your content right in the prompt box. Figma does this. Desktop app only for now.

import type { OpenAIUiToolMetadata } from "@openai/mcp-extensions/server";

// Pass this as _meta when you register your MCP App tool.
// "global" puts your app in ChatGPT's left sidebar, opened fullscreen.
// Use { type: "thread" } instead to open beside a conversation.
const toolMetadata = {
  ui: { resourceUri: "ui://my-app/main" },
  "openai/ui": {
    entrypoints: [{ type: "global" }],
  } satisfies OpenAIUiToolMetadata,
};

To see every extension working at once, install OpenAI’s sample plugin, Bits & Bolts, from the extensions page. The full spec and SDK examples are in the GitHub repo linked from there.

Package it into a folder, then a ZIP

The plugin people install is a folder. At the root, a plugin.json says who you are and what the listing looks like, and an mcp.json says where your server lives.

pdf-to-sheet/
├── plugin.json        ← who you are + the listing
├── mcp.json           ← where your server lives
├── skills/            ← optional instructions
│   └── get-started/SKILL.md
└── assets/
    ├── logo.png       ← square, 48px or bigger
    └── icon.png

{
  "$schema": "https://agent-plugins.org/schemas/1.0.0/plugin.schema.json",
  "name": "pdf-to-sheet",
  "version": "1.0.0",
  "description": "Turn tables in a PDF into a clean spreadsheet.",
  "author": { "name": "Your Name", "email": "you@yourdomain.com" },
  "extensions": {
    "com.openai": {
      "interface": {
        "displayName": "PDF to Sheet",
        "shortDescription": "Turn PDF tables into sheets",
        "longDescription": "Upload a PDF with tables. PDF to Sheet finds each table and returns it as a spreadsheet you can open or download. It works on text-based PDFs; scanned images may come back incomplete.",
        "developerName": "Your Name",
        "category": "Productivity",
        "capabilities": ["Extract tables", "Export spreadsheets"],
        "websiteURL": "https://yourdomain.com",
        "supportURL": "https://yourdomain.com/support",
        "privacyPolicyURL": "https://yourdomain.com/privacy",
        "termsOfServiceURL": "https://yourdomain.com/terms",
        "defaultPrompt": [
          "Turn the table in this PDF into a spreadsheet.",
          "Pull every table out of this bank statement."
        ],
        "logo": "./assets/logo.png",
        "composerIcon": "./assets/icon.png"
      }
    }
  }
}

{
  "$schema": "https://agent-plugins.org/schemas/1.0.0/mcp.schema.json",
  "mcpServers": {
    "pdf": { "type": "streamable-http", "url": "https://yourdomain.com/mcp" }
  }
}

Shortcut: in ChatGPT’s Work mode or in Codex, the built-in @plugin-creator skill scaffolds the folder for you. It uses an older layout (.codex-plugin/plugin.json), which OpenAI still accepts.

Get verified and get your four pages up

• Verify yourself. In your OpenAI organization settings, complete individual or business verification. The directory shows the name you verify under. Only organization owners can submit, unless an owner gives you the Apps Management Write role.
• Four public HTTPS pages: a website, a support page, a privacy policy and terms of service. All four are required for a plugin with a server.
• The privacy policy has to be specific: what you collect, why, who gets it, how long you keep it, and what users can control.

Upload the ZIP and clear the automated checks

1. Open Plugins in the OpenAI dashboard and choose Upload new or existing plugin. Pick your verified identity, then upload the ZIP.
2. Under Metadata & Skills, wait for the checks and read any issues. Fix them in your folder and upload a new ZIP.
3. Under MCPs, connect your server and pass domain verification: serve the exact token the dashboard shows, as plain text, at https://yourdomain.com/.well-known/openai-apps-challenge. Just the token, not JSON.
4. Wait for the tool scan and fix anything it flags.

Submit for review

The review team actually tests your plugin, so give them everything they need. You can put most of this inside plugin.json under extensions.com.openai.review so it imports with the ZIP:

• Exactly 5 positive test cases: the scenario, the prompt, which tools should run, and what should come back. Run every one yourself first.
• Exactly 3 negative test cases: prompts your plugin should refuse or not act on, and what it should do instead.
• A video walkthrough of those cases, at a link reviewers can open.
• A test account if your app needs sign-in, with sample data and no 2FA, email codes or magic links. These go in the dashboard, never in the ZIP.
• Release notes for the version you’re submitting.

Then choose Submit for review and agree to the policy attestations. Feedback arrives by email. If you’re rejected and disagree, reply to that email to appeal.

Publish, then keep improving it

Once it’s approved, nothing goes live until you open the approved version and hit Publish plugin. It then shows up in the one directory ChatGPT and Codex share.

• Server changes ship on their own. OpenAI rescans your server daily, and changes that pass the checks go live without a new ZIP. Hit Rescan to speed it up.
• Listing, skill or config changes need a new ZIP, and that version gets reviewed again.
• Changing your server’s URL later means contacting support. Pick the domain you’ll keep.