How to add an MCP server to ChatGPT (developer mode and connectors)

TL;DR. There are two ways to add an MCP server to ChatGPT. If the server is a listed app, open its listing, click Connect and approve: one click, no settings. For any other server, turn on Developer Mode (Settings, Connectors, Advanced, Developer Mode), click Create, paste the MCP server URL and choose OAuth; that is a custom connector. ChatGPT only talks to remote HTTPS MCP servers, never a local stdio process. Hatchable is a listed app, so the one-click route is enough.

MCP in ChatGPT: connectors, apps and Developer Mode

ChatGPT's connectors are MCP servers underneath. The Model Context Protocol is the open standard that lets a chat client discover a server's tools, call them, and show the results in the conversation, and it is the same standard Claude, Cursor and Gemini use (what is MCP). As of August 2026 OpenAI uses three words around it: connectors for first-party integrations such as Google Drive and GitHub, apps for third-party servers that have been reviewed and listed in a directory, and Developer Mode for pasting any remote server's URL yourself. In July 2026 OpenAI folded the app directory into a plugin directory shared with Codex, so the menu you see may say Apps or Plugins; existing listing links keep working. A custom connector and a Developer Mode app are the same thing: an MCP server you added by URL.

Route 1: connect a listed app (one click)

1. Open the listing

   Either follow a direct link, like Hatchable in the ChatGPT app directory, or open the Apps (or Plugins) section inside ChatGPT and search by name.

2. Click Connect

   ChatGPT hands you to the provider's sign-in page. For Hatchable that is an OAuth screen on hatchable.com; approving it creates the free account if you do not have one. Nothing to paste, no key to copy.

3. Use it in a chat

   Name the app in your message ("... on Hatchable") or pick it from the + menu in the composer. The tools appear as the model calls them.

Listed apps do not need Developer Mode and, as of August 2026, connect on any ChatGPT plan including free accounts. The full click-through for Hatchable is at connect Hatchable to ChatGPT.

Route 2: Developer Mode for any remote MCP server

Developer Mode is OpenAI's beta for full MCP client support, read and write tools included. OpenAI's documentation lists it as available to Plus, Pro, Business, Enterprise and Education accounts on the web app (as of August 2026). Free accounts do not get it, and on Business and Enterprise workspaces an owner has to enable it first.

1. Turn on Developer Mode

   Open Settings, then Connectors, then Advanced, and switch on Developer Mode. OpenAI has moved this toggle during 2026 (its developer docs currently also describe it under Settings, Security and login), so if it is not under Connectors, look there.

2. Create the connector

   Back on the Connectors page, click Create. Give it a name and a short description, paste the MCP server URL (for Hatchable, https://hatchable.com/mcp), and choose OAuth as the authentication. Pick No authentication only for a server that genuinely has none. Save, then Connect and complete the sign-in.

3. Select it in a chat

   In a new conversation open the + menu, choose Developer Mode, and tick the connector. Ask for something the server can do; ChatGPT lists the tools it found and starts calling them.

How the tools behave once connected

ChatGPT fetches the server's tool list when you connect and again when you pick it in a conversation. Read tools run when the model decides they help. Write tools, anything that creates, changes or sends, ask for your confirmation by default with the exact input shown, and you can choose to remember the answer for the rest of that conversation. Results come back into the chat as text and links. Hatchable is a plain set of MCP tools in ChatGPT (create a project, write files, run SQL, deploy), so the app it builds opens at its own URL rather than inside the chat.

Worked example: ChatGPT building and deploying on Hatchable

Connect Hatchable by Route 1, start a fresh chat, and ask: "Build a waitlist page for my side project with an email form that stores signups in a database, and put it live on Hatchable." ChatGPT calls the Hatchable tools in turn: create a project, write the HTML and a small SQL migration, deploy. It comes back with a live your-app.hatchable.site link. Every project starts with a private Postgres database, sign-in for its users, email, scheduled jobs and file storage, so the follow-up ("add an admin page that lists the signups") is another prompt, not another service. The free plan gives unlimited private projects and one published app with no card; Builder is $12 a month for unlimited published apps. More on the ChatGPT route in deploy an app from ChatGPT, and the tool list in the MCP developer docs.

Troubleshooting

• No Create button. Developer Mode is off, the account is on a free plan, or a workspace owner has not enabled it.
• Connection failed. The URL must be https:// and public. A localhost address or a plain http:// URL will not work.
• Connected, but ChatGPT never uses it. Select the connector in the + menu for that conversation (Developer Mode apps are chosen per chat), or name the app in the prompt.
• Sign-in keeps looping. Disconnect the app on the Connectors page, then connect again and finish the OAuth screen in the same browser.

General characterisations based on OpenAI's public documentation as of August 2026. Plan availability and menu names change, so check OpenAI's current help pages for the details that matter to you.