Connect MCP clients

Connect ChatGPT

ChatGPT connects to remote MCP servers as custom apps. OpenAI previously called these "custom connectors", and some ChatGPT screens still use connector language, but the current ChatGPT docs use apps as the primary term.

To add a Zuplo MCP Gateway route to ChatGPT, enable Developer Mode, create an app that points at the gateway's public MCP route URL, scan the tools, and complete the OAuth flow.

OpenAI's current ChatGPT docs describe full MCP app support, including write/modify actions, as a beta for ChatGPT Business, Enterprise, and Edu plans on ChatGPT web. Pro users can connect MCP servers with read/fetch permissions in Developer Mode, but full MCP support is not currently available to Pro users. Check OpenAI's Developer mode and MCP apps in ChatGPT article for the latest plan availability.

Prerequisites

A Zuplo project with the MCP Gateway plugin configured and at least one MCP route. See the quickstart if you haven't set one up yet.
A ChatGPT Business, Enterprise, or Edu workspace for full MCP apps. Pro users can use read/fetch MCP servers only.
Developer Mode enabled for the ChatGPT account or workspace. OpenAI's current Apps SDK guide says to enable it from Settings → Apps & Connectors → Advanced settings. Business and Enterprise/Edu workspaces may require an admin or owner to enable Developer Mode first from workspace settings.
A public HTTPS MCP route URL. ChatGPT does not connect directly to localhost or private-network MCP servers. For local or private development, use OpenAI's Secure MCP Tunnel or another HTTPS tunnel.
If your gateway uses OAuth, the identity provider should support the MCP authorization requirements ChatGPT expects. For long-lived connections, verify that your provider can issue refresh tokens; OpenAI recommends advertising and requesting the offline_access scope when using OpenID Connect.

Get the route URL

Each MCP route in config/routes.oas.json is reachable at https://{deploymentUrl}/{routePath} once deployed — for example https://{deploymentUrl}/mcp/linear-v1.

Add the app

Enable Developer Mode.

In ChatGPT web, open Settings → Apps & Connectors → Advanced settings and enable Developer Mode. In Business, Enterprise, or Edu workspaces, an admin or owner may need to enable Developer Mode from workspace settings first. See OpenAI's Developer mode and MCP apps in ChatGPT article for the current plan-specific path.
Create an app.

Open Settings → Apps & Connectors and click Create. In some workspaces, the create flow is under Workspace settings → Apps → Create.
Enter the gateway app details.

Provide a name, description, and the gateway route URL. Use the public MCP route URL as the app or connector URL, for example https://{deploymentUrl}/mcp/linear-v1.
Choose the authentication method.

If the gateway route is protected, choose OAuth or the OAuth/OpenID Connect option in ChatGPT. The Zuplo gateway exposes the MCP OAuth metadata ChatGPT needs for discovery.
Scan the gateway tools.

Click Scan Tools. If ChatGPT opens an authorization prompt, complete the gateway sign-in with the identity provider you configured for the route. Wait for ChatGPT to finish scanning and show the tools exposed by the gateway.
Complete the upstream connection.

If the upstream MCP server also requires per-user OAuth, the gateway shows a consent page with that upstream server. Click Connect, complete the upstream OAuth flow, then click Authorize to return to ChatGPT.
Create the app.

Click Create after the scan succeeds. ChatGPT shows the app as a Developer Mode app for your account, or as a draft app in workspace settings.
Use the app in a chat.

Start a new chat, click the + button near the message composer, choose More, and select your app. Prompt ChatGPT with a request that should use one of the gateway tools.

Publish for a workspace

Developer Mode apps are private while you test them. To make the app available to a Business, Enterprise, or Edu workspace, an admin or owner must publish it from Workspace settings → Apps. OpenAI notes that workspace apps use a reviewed snapshot of the available tools; after changing the gateway's tools or tool schemas, refresh the app's actions in ChatGPT before publishing or republishing.

What ChatGPT supports

ChatGPT acts as an MCP client for the gateway. For authenticated MCP servers, OpenAI's Apps SDK authentication guide says ChatGPT supports Client ID Metadata Documents (CIMD), Dynamic Client Registration (DCR), predefined OAuth clients, and Authorization Code with PKCE. The gateway handles the resource metadata and OAuth challenge flow for MCP clients.

ChatGPT supports:

Tools — invoke gateway-exposed tools from the conversation. Full MCP apps no longer need to expose only search and fetch tools, though company knowledge and deep research still use read/fetch-style access.
MCP Apps — render interactive HTML widgets inline through the OpenAI Apps SDK conventions. The Apps SDK is built on top of MCP.

ChatGPT doesn't currently consume arbitrary MCP prompts, roots, sampling, or elicitation from a remote MCP server.

Build an Apps SDK app on top of the gateway

If you're authoring an MCP server intended to render rich UI inside ChatGPT, read OpenAI's Apps SDK documentation — the Apps SDK builds on the MCP Apps extension, so an Apps SDK app is an MCP server with UI conventions on top. The Zuplo MCP Gateway forwards Apps-related metadata (_meta.ui.*) from upstream MCP servers unchanged. Tool authors who want to ship UI to ChatGPT should follow the Apps SDK guide; the gateway transparently relays the additional metadata to the client.

For more background on Apps SDK and Zuplo-hosted MCP servers, see OpenAI Apps SDK with Zuplo.

Troubleshooting

Create or Developer Mode isn't visible. Confirm your plan supports the level of MCP access you need. Full MCP apps currently require ChatGPT Business, Enterprise, or Edu. Your workspace admin may also need to enable Developer Mode or grant access with RBAC.
Sign-in succeeds but no tools appear. Tools only appear when ChatGPT decides to invoke them. Try a prompt that mentions the action you want to take. If the app is not selected from the composer, ChatGPT doesn't see any of its tools.
Tool scan fails. Confirm the MCP route is reachable over public HTTPS and that the route returns the MCP OAuth metadata ChatGPT expects. Localhost and private-network URLs require a tunnel.
OAuth fails with a redirect error. ChatGPT registers its redirect URI through CIMD, DCR, or a predefined OAuth client, depending on how the app is configured. If your identity provider blocks dynamic redirect URIs, use CIMD or pre-register the redirect URL ChatGPT shows on the app management page.
Users have to reauthenticate often. Check whether your identity provider issues refresh tokens. OpenAI's ChatGPT docs call out offline_access for OpenID Connect providers.

Connect MCP clients overview
OpenAI's Apps SDK documentation
OpenAI's Connect from ChatGPT guide
OpenAI's Developer mode and MCP apps in ChatGPT article
OpenAI Apps SDK with Zuplo
Authentication overview

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Last modified on August 24, 2026

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Prerequisites

A Zuplo project with the MCP Gateway plugin configured and at least one MCP route. See the quickstart if you haven't set one up yet.

A ChatGPT Business, Enterprise, or Edu workspace for full MCP apps. Pro users can use read/fetch MCP servers only.

Developer Mode enabled for the ChatGPT account or workspace. OpenAI's current Apps SDK guide says to enable it from Settings → Apps & Connectors → Advanced settings. Business and Enterprise/Edu workspaces may require an admin or owner to enable Developer Mode first from workspace settings.

A public HTTPS MCP route URL. ChatGPT does not connect directly to localhost or private-network MCP servers. For local or private development, use OpenAI's Secure MCP Tunnel or another HTTPS tunnel.

If your gateway uses OAuth, the identity provider should support the MCP authorization requirements ChatGPT expects. For long-lived connections, verify that your provider can issue refresh tokens; OpenAI recommends advertising and requesting the offline_access scope when using OpenID Connect.

Add the app

Enable Developer Mode.

In ChatGPT web, open Settings → Apps & Connectors → Advanced settings and enable Developer Mode. In Business, Enterprise, or Edu workspaces, an admin or owner may need to enable Developer Mode from workspace settings first. See OpenAI's Developer mode and MCP apps in ChatGPT article for the current plan-specific path.
Create an app.

Open Settings → Apps & Connectors and click Create. In some workspaces, the create flow is under Workspace settings → Apps → Create.
Enter the gateway app details.

Provide a name, description, and the gateway route URL. Use the public MCP route URL as the app or connector URL, for example https://{deploymentUrl}/mcp/linear-v1.
Choose the authentication method.

If the gateway route is protected, choose OAuth or the OAuth/OpenID Connect option in ChatGPT. The Zuplo gateway exposes the MCP OAuth metadata ChatGPT needs for discovery.
Scan the gateway tools.

Click Scan Tools. If ChatGPT opens an authorization prompt, complete the gateway sign-in with the identity provider you configured for the route. Wait for ChatGPT to finish scanning and show the tools exposed by the gateway.
Complete the upstream connection.

If the upstream MCP server also requires per-user OAuth, the gateway shows a consent page with that upstream server. Click Connect, complete the upstream OAuth flow, then click Authorize to return to ChatGPT.
Create the app.

Click Create after the scan succeeds. ChatGPT shows the app as a Developer Mode app for your account, or as a draft app in workspace settings.
Use the app in a chat.

Start a new chat, click the + button near the message composer, choose More, and select your app. Prompt ChatGPT with a request that should use one of the gateway tools.

Publish for a workspace

What ChatGPT supports

ChatGPT supports:

Tools — invoke gateway-exposed tools from the conversation. Full MCP apps no longer need to expose only search and fetch tools, though company knowledge and deep research still use read/fetch-style access.

MCP Apps — render interactive HTML widgets inline through the OpenAI Apps SDK conventions. The Apps SDK is built on top of MCP.

ChatGPT doesn't currently consume arbitrary MCP prompts, roots, sampling, or elicitation from a remote MCP server.

Build an Apps SDK app on top of the gateway

For more background on Apps SDK and Zuplo-hosted MCP servers, see OpenAI Apps SDK with Zuplo.

Troubleshooting

Create or Developer Mode isn't visible. Confirm your plan supports the level of MCP access you need. Full MCP apps currently require ChatGPT Business, Enterprise, or Edu. Your workspace admin may also need to enable Developer Mode or grant access with RBAC.

Sign-in succeeds but no tools appear. Tools only appear when ChatGPT decides to invoke them. Try a prompt that mentions the action you want to take. If the app is not selected from the composer, ChatGPT doesn't see any of its tools.

Tool scan fails. Confirm the MCP route is reachable over public HTTPS and that the route returns the MCP OAuth metadata ChatGPT expects. Localhost and private-network URLs require a tunnel.

OAuth fails with a redirect error. ChatGPT registers its redirect URI through CIMD, DCR, or a predefined OAuth client, depending on how the app is configured. If your identity provider blocks dynamic redirect URIs, use CIMD or pre-register the redirect URL ChatGPT shows on the app management page.

Users have to reauthenticate often. Check whether your identity provider issues refresh tokens. OpenAI's ChatGPT docs call out offline_access for OpenID Connect providers.

Prerequisites

Get the route URL

Add the app

Publish for a workspace

What ChatGPT supports

Build an Apps SDK app on top of the gateway

Troubleshooting

Related

Prerequisites

Get the route URL

Add the app

Publish for a workspace

What ChatGPT supports

Build an Apps SDK app on top of the gateway

Troubleshooting

Related