---
title: "Connecting Claude · EenFactuurMaken.nl"
description: "Connect Claude.ai, Claude Desktop and Claude Code to EenFactuurMaken.nl with OAuth or an API key."
url: "https://eenfactuurmaken.nl/en/docs/mcp/claude"
markdown_url: "https://eenfactuurmaken.nl/en/docs/mcp/claude.md"
language: "en-GB"
---

# Connecting Claude

Connect Claude.ai, Claude Desktop and Claude Code to EenFactuurMaken.nl with OAuth or an API key.

## Claude.ai and Claude Desktop (OAuth)

The easiest way: a custom connector with OAuth.

1. In Claude, go to **Settings → Connectors**.
2. Choose **Add custom connector**.
3. Enter `EenFactuurMaken.nl` as the name and `https://eenfactuurmaken.nl/mcp` as the URL.
4. Click **Connect**, sign in to EenFactuurMaken.nl and give permission.
5. In a chat, turn on EenFactuurMaken.nl in the tools and connectors menu.

A connector you add on claude.ai also works in Claude Desktop. Whether custom connectors are included in your plan is explained by Anthropic.

## Claude Desktop with an API key

Prefer an API key? In Claude Desktop open **Settings → Developer → Edit Config** and put this in `claude_desktop_config.json`:

```json
{
  "mcpServers": {
    "eenfactuurmaken": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "https://eenfactuurmaken.nl/mcp", "--header", "Authorization:${EENFACTUURMAKEN_AUTH}"],
      "env": { "EENFACTUURMAKEN_AUTH": "Bearer efm_your_key" }
    }
  }
}
```

Then restart Claude Desktop. This needs [Node.js](https://nodejs.org): `mcp-remote` connects Claude Desktop to our server. The key lives in `env` so the space in "Bearer …" also works on Windows.

## Claude Code

One command in your terminal. With OAuth (no header):

```bash
claude mcp add --transport http eenfactuurmaken https://eenfactuurmaken.nl/mcp
```

Then type `/mcp` in Claude Code, choose `eenfactuurmaken` and **Authenticate**. Your browser opens so you can sign in.

Or with an API key:

```bash
claude mcp add --transport http eenfactuurmaken https://eenfactuurmaken.nl/mcp \
  --header "Authorization: Bearer efm_your_key"
```

You can also set up the server per project in `.mcp.json`:

```json
{
  "mcpServers": {
    "eenfactuurmaken": {
      "type": "http",
      "url": "https://eenfactuurmaken.nl/mcp",
      "headers": { "Authorization": "Bearer ${EENFACTUURMAKEN_API_KEY}" }
    }
  }
}
```

Put the key in the `EENFACTUURMAKEN_API_KEY` environment variable and not in the file, especially if you commit it to git.

## Try it

Ask for example: _"Show my outstanding invoices"_ or use the **create-invoice** prompt from the prompt menu. See [All tools](https://eenfactuurmaken.nl/en/docs/mcp/tools#prompts).

Last updated on 13 October 2026