Integration Guide
ChatGPT + WHMCS
Connect ChatGPT to WHMCS in under 15 minutes
Estimated time: 15 minutes · Transport: Remote HTTP/SSE only
Beta feature. Requires ChatGPT Plus, Pro, or Team plan.
Quick Reference
- Plan Required
- ChatGPT Plus/Pro/Team (web app)
- Transport
- Remote HTTP/SSE
- Public URL
- Required
- Node.js
- Not required
- Free Tier MCP
- No (paid plan only)
- Tools per Turn
- 3 per turn (beta limitation)
- Avg Response Time
- 3-6 seconds (includes network round-trip to your server)
ChatGPT MCP Support is in Beta
- MCP support in ChatGPT has been available since September 2025 and is still in beta.
- It requires a ChatGPT Plus ($20/month), Pro ($200/month), or Team plan. The free tier does not support MCP.
- ChatGPT only supports remote MCP servers (HTTPS). It does not support localhost or STDIO connections.
- For the most stable MCP experience, we recommend Claude Desktop as your primary client.
Prerequisites
- WHMCS 8.0 or higher with admin access
- MCP Server addon installed and activated (installation guide)
- ChatGPT Plus, Pro, or Team subscription (chatgpt.com)
- A publicly accessible WHMCS URL with HTTPS (required for remote MCP connections)
Step 1: Generate an API Key
- Go to your WHMCS admin panel
- Navigate to Addons > MCP Server
- Click Generate New API Key
- Copy the API key and save it securely. You will need it in the next steps.
Important: The API key is shown only once. If you lose it, you will need to generate a new one.
Step 2: Ensure a Public HTTPS URL
ChatGPT runs in the cloud, so it needs to reach your MCP Server over the internet. Your WHMCS must be accessible via HTTPS.
If your WHMCS is already publicly accessible
Most production WHMCS installations are already accessible via HTTPS. Verify by opening this URL in your browser:
https://your-whmcs.com/modules/addons/mx_mcp/mcp.phpIf it loads without errors, you are ready to proceed to Step 3.
If your WHMCS is behind a firewall or on localhost
You need a way to expose your MCP Server to the internet. Options include:
- Reverse proxy: Configure Nginx or Apache to forward a public subdomain to your WHMCS MCP endpoint
- Cloudflare Tunnel: Use
cloudflared tunnelto expose your local WHMCS to the internet securely - ngrok: For testing, run
ngrok http 443to get a temporary public URL
Security note: When exposing your MCP Server publicly, always use HTTPS and strong API keys. The MCP Server addon validates API keys on every request, but make sure your WHMCS admin panel is not exposed without its own authentication.
Step 3: Add MCP Server in ChatGPT
- Go to chatgpt.com and sign in
- Click your profile icon in the top-right corner
- Go to Settings
- Navigate to Connected Apps (or MCP Servers in some versions)
- Click Add MCP Server
- Enter your MCP Server details:
// ChatGPT MCP Setup (via Settings UI)
// 1. Go to ChatGPT > Settings > Connected Apps > Add MCP Server
// 2. Enter your WHMCS MCP Server URL and Bearer token:
Server URL: https://your-whmcs.com/modules/addons/mx_mcp/mcp.php
Authorization: Bearer YOUR_BEARER_TOKEN
// Important: Your MCP Server must be publicly accessible (HTTPS)
// ChatGPT does NOT support localhost/STDIO connections
// If your WHMCS is behind a firewall, use a reverse proxy or tunnel- Click Save or Connect
- ChatGPT will attempt to verify the connection. If successful, the server will appear in your connected apps list.
Step 4: Test the Connection
- Start a new conversation in ChatGPT
- Type:
Get WHMCS system status - ChatGPT may ask for permission to use the MCP tool. Click Allow.
- If the connection is working, you should see system information from your WHMCS installation
Success! If you see WHMCS system info, the connection is working. Try queries like “Show all overdue invoices” or “List active clients”.
Troubleshooting
“Connected Apps” not visible in Settings
- MCP support requires ChatGPT Plus ($20/month), Pro ($200/month), or Team plan
- The free tier does not support MCP server connections
- If you have a paid plan but do not see the option, try logging out and back in
- MCP support is still in beta and may roll out gradually. Check OpenAI announcements for updates.
“Cannot connect to server”
- ChatGPT can only connect to publicly accessible HTTPS URLs. It cannot reach localhost or private network addresses.
- Verify your WHMCS URL is reachable from outside your network (test in a browser on your phone or a different network)
- Ensure your SSL certificate is valid and not self-signed (ChatGPT may reject self-signed certificates)
- If using a tunnel (ngrok, Cloudflare Tunnel), make sure it is still running
ChatGPT does not use MCP tools
- MCP support in ChatGPT is in beta. Some sessions may not pick up tools automatically.
- Try being explicit: “Use the WHMCS MCP tools to get the system status”
- Start a new conversation if tools are not appearing in the current one
- Check Settings > Connected Apps to verify the server shows as “Connected”
“Permission denied”
- Your API key may not have the required permissions
- Go to Addons > MCP Server in WHMCS and check API key permissions
- Ensure the API key has access to the tools you are trying to use
Upgrading from v1.1.x?
If you set up the MCP Server before v1.3.0, the authentication method changed. Here is what is different and how to update your config.
Previous method (v1.1.x)
Still works. In v1.3.0, authentication changed from API Keys to Bearer tokens, and the endpoint changed from sse.php to mcp.php. If you are still on v1.1.x, the old server URL and auth header were:
// Old server URL (v1.1.x): https://your-whmcs.com/modules/addons/mx_mcp/mcp/sse.php // Old authentication header: MCP_API_KEY: your-api-key-here
To upgrade: update the server URL to use mcp.php and replace the MCP_API_KEY header with Authorization: Bearer YOUR_TOKEN.