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You need a Baselayer account with an active plan. If you do not have one, the sign-in page links to self-serve sign-up.Custom connectors in ChatGPT require Developer mode, which is available on Plus, Pro, Business, Enterprise, and Edu plans. Turn it on in ChatGPT’s settings before you add the connector.On Business, Enterprise, and Edu workspaces an admin must enable connectors for members.

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ChatGPT Desktop & Web

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Entry point

Make sure Developer mode is on before you continue.
  • ChatGPT web (chatgpt.com): open Plugins from the left sidebar, then click + New Plugin.
  • ChatGPT Desktop: you can’t create or configure MCP plugins here. Set up the Baselayer plugin on the web, and it then works in the desktop app too.

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Add Baselayer as a connector

  1. Open Plugins from the left sidebar, then click + New Plugin. Don’t use the “Connect to a custom MCP” quick-add form on the separate MCPs tab. It only supports Bearer-token or header authentication and has no OAuth fields, so it won’t work for this integration.
  2. Fill in the form:
  3. Expand Advanced OAuth settings.
  4. Under Registration method, select User-Defined OAuth Client.
  5. Enter the following values:
  6. Leave the remaining advanced OAuth settings unchanged.
  7. Check I understand and want to continue.
  8. Click Create.
  9. In the popup, click Sign in with Baselayer.
  10. Sign in with your Baselayer credentials. If you do not have an account, use the Sign up link on that page.
  11. Click Allow on the consent screen (“Search and verify businesses with Baselayer on your behalf”). The browser returns you to the Baselayer plugin’s detail page, showing it connected with its tools listed.
Click Try in chat to start a new conversation with Baselayer enabled and try it with one of the Example prompts below.

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Remove Baselayer as a connector

To sign out without deleting your configuration, open Plugins, find Baselayer, click the ’⋯’ menu, and choose Disconnect. This revokes your session but keeps the connector’s configuration. To remove the connector entirely (required before you can change the Registration method or other stored OAuth settings), use the same ’⋯’ menu and choose Manage instead. This opens the plugin’s settings page. Click the ’⋯’ menu there and choose Delete.

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Codex CLI

Codex CLI is not supported. It registers with the identity provider in a way Baselayer’s provider does not accept. For terminal workflows, use Claude Code.

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Example prompts

  • “Verify Acme Holdings LLC at 500 Main St, Austin TX 78701 and tell me whether the EIN 12-3456789 matches.”
  • “Run a full KYB on Acme Holdings LLC with website analysis and industry classification, then summarize the risk signals.”
  • “Screen Jane Doe against OFAC and PEP.”
  • “Check for UCC filings, tax liens, litigation, and bankruptcies against Acme Holdings LLC in Texas.”
  • “Find Ray’s Famous Pizza’s website and social profiles and summarize what customers say in reviews.”
ChatGPT chooses the right tool from the tool list. Tools that start paid work, such as a new search, ask for your confirmation before running unless you approve them for the conversation; read tools run without a prompt.

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Organization and application

ChatGPT does not let you attach headers to a connector, so tool calls always run in your default organization’s production application. If you belong to several organizations, or want sandbox data, use Claude Code or the REST API instead.

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Troubleshooting

If you see “Your admin has not enabled developer mode” and the Developer mode toggle is greyed out, your ChatGPT workspace is on Business, Enterprise, or Edu, and a workspace admin has not turned on Developer mode for members yet. You cannot enable this yourself. Ask your workspace admin to turn it on, then return to Settings → Security and login. If you get “Client not found” or a login error after entering the URL, the OAuth Client ID was mistyped, or something was entered in the Client Secret field. That field must stay empty. Re-enter Client ID chatgpt-connector exactly and leave Client Secret blank. If the Baselayer sign-in page says “We are sorry… Client Metadata fetch failed”, go back and check that the Connection URL and Authentication method from step 2 are correct. Then open the plugin’s Advanced OAuth settings and set Registration method to User-Defined OAuth Client with Client ID chatgpt-connector, secret blank, and Token endpoint auth method none, as described above. If sign-in completes but the connector shows an error, your account must belong to an organization with at least one enabled application. Sign in to the Console to confirm, then reconnect. If a tool returns “Caller lacks the required permission”, your role does not include that product. The permissions table names the permission each tool needs; an organization admin can grant it in the Console under Members. For anything else, email support@baselayer.com.