How to make a ChatGPT plugin in 2026: build, test, submit

01What is a ChatGPT plugin now?

A plugin is what you submit to the ChatGPT Directory, the store inside ChatGPT. OpenAI's plugin guidelines say a plugin can hold MCP tools, skills, or both, with optional UI, and that the directory is shared by ChatGPT and Codex. A skill is a set of written instructions for a repeatable task. To connect ChatGPT to your own product, you need the MCP server.

OpenAI's help center separates two words. An app connects ChatGPT to a service. A plugin packages apps and skills for a task (OpenAI). Older articles call directory submissions "ChatGPT apps", and OpenAI's Apps SDK docs now redirect to its plugins docs.

02What happened to the 2023 ChatGPT plugins?

In 2023 a plugin was your API, described by an OpenAPI spec and a manifest file (OpenAI). OpenAI's quickstart kept the manifest at .well-known/ai-plugin.json. OpenAI wound down that beta in favour of GPTs. New plugin conversations stopped on 19 March 2024, and existing ones ended on 9 April 2024. The name came back for a different system.

03How do I make a ChatGPT plugin?

1. Pick the tasks. List what customers ask about or do with your product: check an order, find a product, book a slot. Each task becomes one tool. OpenAI doesn't accept a generic tool that runs any operation.
2. Build the MCP server. OpenAI's build guide uses the official MCP SDKs and a streamable HTTP endpoint, usually at /mcp. Give each tool a verb name, a description that says when to use it, an input schema and annotations. Starting from an API: turn your API into an MCP server. Naming and descriptions: tool design best practices.
3. Add UI only where it helps. OpenAI calls custom UI optional. ChatGPT supports the open MCP Apps standard: a tool points to an HTML resource at a ui:// address, and ChatGPT shows it as an inline card, a carousel, full screen or picture-in-picture (OpenAI). List every domain the UI loads from in its content security policy. Review compares that list with what the UI does.
4. Add sign-in with OAuth. Public data needs none. Customer data needs OAuth 2.1: your server publishes /.well-known/oauth-protected-resource, your login service supports PKCE with S256, and each tool declares noauth, oauth2 or both (OpenAI). Using the login you already have: MCP server authentication.
5. Test it in ChatGPT. Host the server at a public HTTPS address, add it as a custom MCP server and try real prompts. The steps are below.
6. Run a directory check. npx mcp-directory-check <your server URL> checks the server against ChatGPT's and Claude's published rules. It reads the tool list and metadata without calling a tool or signing in (GitHub).
7. Package and submit. Verify your OpenAI organization, prove you own the domain, upload the ZIP in the Plugins dashboard, fix what the automated checks find, fill in the review details and submit (OpenAI). The full checklist: ChatGPT app directory.
8. Publish after approval. Approval doesn't list you. You choose when to select Publish plugin.

04Which SDK do I use for a ChatGPT plugin?

OpenAI's help center describes the Apps SDK as built on MCP and open source (OpenAI). In OpenAI's build docs, the code uses these packages:

ChatGPT-only features, such as file uploads and checkout, sit on window.openai. OpenAI says to check each one exists and have a fallback.

05How do I test a ChatGPT plugin?

Step by step, with plans and fixes: how to add an MCP server to ChatGPT.

Start the Inspector with:

npx @modelcontextprotocol/inspector@latest

In ChatGPT, open Plugins, select the plus button, then Add custom MCP server. Enter the URL, set the sign-in type, accept the risk warning and select Create as a plugin. Install it, type @ in a new chat and pick it (OpenAI). Try direct, indirect, follow-up, write and unsupported requests, and note which tool ran with which inputs. After a change, select Refresh and start a new chat.

You don't turn on developer mode any more. OpenAI's help center says the risk warning for each server replaces that step (OpenAI). The same page lists full MCP support for Business and Enterprise/Edu on the web. On Business, only admins and owners can add a server. Pro users can connect custom servers with read and fetch permissions only, and none can be added on mobile.

A server on your own computer needs a tunnel to be reachable for testing. The submission needs a public HTTPS address.

06What does OpenAI check in plugin review?

From OpenAI's submission guide, plugin guidelines and app review page:

The app review page lists the common reasons for rejection:

• Connection failures. The reviewer couldn't reach the server or sign in with the test account.
• Failed test cases. Results didn't match what you said they would, or the UI didn't load properly.
• Undisclosed data. A tool returned user data that your privacy policy doesn't cover.
• Wrong annotations. A hint doesn't match what the tool does, such as a tool marked read-only that writes.

A tool that only reads your own catalog would set:

"annotations": {
  "readOnlyHint": true,
  "destructiveHint": false,
  "openWorldHint": false
}

Field limits, icons and the package layout: what you need to submit.

07How long does ChatGPT plugin review take?

OpenAI doesn't publish a review time. Its app review page says timelines vary, asks developers not to contact support to speed one up, and gives no estimates for update reviews. Only one review per plugin can run at a time, and feedback comes by email.

WarrantyWarden's plugin, where people sign in with their existing WarrantyWarden account, was submitted by 13 October 2026 and approved on 29 October 2026.

08Can I make a ChatGPT plugin without coding?

Yes. Transica builds and hosts the server from a business's own API or website. ChatGPT's Plugin Creator makes plugins for you or your workspace.

To use Plugin Creator, install it from the plugin directory and start a chat with @plugin-creator (OpenAI). Publishing to a workspace directory doesn't publish to the public one. Transica serves tools without custom UI, so a plugin with its own screens needs your own server. The routes side by side: five ways to build an MCP server.

10Common questions