Connect ChatGPT

This guide connects ChatGPT to your WHMCS through Relyagent. Relyagent turns WHMCS into a self-hosted MCP server — an open standard that lets AI assistants call external tools — so ChatGPT can list and call only the WHMCS tools you allow.

Developer-mode connectors required

Custom connectors in ChatGPT live behind developer mode, which needs a ChatGPT plan that supports developer-mode connectors. If you don't see the option below, your plan may not include it.

Prerequisites

• A connection created under Addons → Relyagent → MCP Clients — see Configuration.

• Its Client ID and Client Secret (the secret is shown only once at creation).

• The shared Endpoint URL:

  https://<your-whmcs>/modules/addons/relyagent/public/mcp/endpoint.php

Grab the exact values from WHMCS

The Setup tab (Addons → Relyagent → Setup) has a ChatGPT accordion with the Endpoint URL pre-filled and copy-paste steps.

Enable developer mode and create the connector

1. In ChatGPT, open Settings → Apps & Connectors → Advanced and turn on Developer mode.
2. Go back to Apps & Connectors and choose Create to add a new connector.
3. Paste the Endpoint URL above as the connector's server URL.
4. Choose OAuth as the authentication method.
5. Enter the connection's Client ID and Client Secret, then create the connector.

Addons → Relyagent → Setup (ChatGPT accordion)

Authorize and consent

After you create the connector, start the authorization:

1. You're sent to your native WHMCS admin login — your existing 2FA, brute-force and IP rules apply, because Relyagent shows no login form of its own.
2. A consent screen lists this connection's tools. Approve it to finish.

Verify it works

Ask ChatGPT what WHMCS tools the connector exposes. It should list only the tools you ticked for this connection — nothing more. Any tool outside that set is rejected.

If it won't connect

Make sure you entered both the Client ID and Client Secret and chose OAuth — the Endpoint URL alone isn't enough. Confirm you signed in at the WHMCS admin login and approved consent, and double-check the exact Endpoint URL. See the error reference.

Related

• Configuration — create and manage connections
• Setup tab: Addons → Relyagent → Setup
• MCP tools — what each tool group does