---
title: "Connecting ChatGPT · EenFactuurMaken.nl"
description: "Add EenFactuurMaken.nl as a connector in ChatGPT (developer mode) and sign in with OAuth. Then create invoices in a chat."
url: "https://eenfactuurmaken.nl/en/docs/mcp/chatgpt"
markdown_url: "https://eenfactuurmaken.nl/en/docs/mcp/chatgpt.md"
language: "en-GB"
---

# Connecting ChatGPT

Add EenFactuurMaken.nl as a connector in ChatGPT (developer mode) and sign in with OAuth. Then create invoices in a chat.

ChatGPT connects with **OAuth**: you sign in to EenFactuurMaken.nl and give permission. You don't need an API key.

## Steps

1. Open ChatGPT in your browser and go to **Settings → Apps & Connectors → Advanced settings**.
2. Turn on **Developer mode**.
3. Choose **Create connector** (or "Create").
4. Fill in:
   - **Name**: `EenFactuurMaken.nl`
   - **MCP server URL**: `https://eenfactuurmaken.nl/mcp`
   - **Authentication**: OAuth
5. Click **Create**. A EenFactuurMaken.nl window opens: sign in (with 2FA if you have it on) and click **Allow**.
6. Start a new chat, pick your EenFactuurMaken.nl connector in the tools menu and ask something, for example: _"How many invoices are outstanding?"_

Menu names change now and then. Can't find it? Search the settings for "connector" or "MCP".

## Good to know

- Developer mode and custom connectors aren't available on every ChatGPT plan. Check with OpenAI which plans support it.
- ChatGPT asks for confirmation before using a tool that changes or sends something.
- The connection appears under **Settings → API & AI → Connected apps** in EenFactuurMaken.nl. You disconnect it there too.

Not working? See [MCP server: troubleshooting](https://eenfactuurmaken.nl/en/docs/mcp#troubleshooting).

Last updated on 13 October 2026