Fortnox MCP Server

An MCP (Model Context Protocol) server for integrating with the Fortnox Swedish accounting system. This server enables LLMs to interact with Fortnox for managing invoices, customers, suppliers, accounts, and vouchers.

Quick Start (Claude Desktop)

1. Get your Fortnox credentials

Register at Fortnox Developer Portal
Create an application to get your Client ID and Client Secret
Complete the OAuth2 flow to get a Refresh Token

2. Add to Claude Desktop

Open your Claude Desktop config file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
Windows: %APPDATA%\Claude\claude_desktop_config.json

Add this configuration:

{
  "mcpServers": {
    "fortnox": {
      "command": "npx",
      "args": ["-y", "fortnox-mcp-server"],
      "env": {
        "FORTNOX_CLIENT_ID": "your-client-id",
        "FORTNOX_CLIENT_SECRET": "your-client-secret",
        "FORTNOX_REFRESH_TOKEN": "your-refresh-token"
      }
    }
  }
}

3. Restart Claude Desktop

That's it! You can now ask Claude to manage your Fortnox invoices, customers, and more.

Features

Customer Management

fortnox_list_customers - List and search customers
fortnox_get_customer - Get customer details
fortnox_create_customer - Create new customer
fortnox_update_customer - Update customer
fortnox_delete_customer - Delete customer

Invoice Management

fortnox_list_invoices - List invoices with filtering
fortnox_get_invoice - Get invoice details with line items
fortnox_create_invoice - Create new invoice
fortnox_update_invoice - Update draft invoice
fortnox_bookkeep_invoice - Bookkeep invoice
fortnox_cancel_invoice - Cancel invoice
fortnox_credit_invoice - Create credit note
fortnox_send_invoice_email - Send invoice by email

Supplier Management

fortnox_list_suppliers - List and search suppliers
fortnox_get_supplier - Get supplier details
fortnox_create_supplier - Create new supplier
fortnox_update_supplier - Update supplier
fortnox_delete_supplier - Delete supplier

Account Management

fortnox_list_accounts - List chart of accounts
fortnox_get_account - Get account details
fortnox_create_account - Create new account
fortnox_update_account - Update account
fortnox_delete_account - Delete account

Voucher Management

fortnox_list_vouchers - List vouchers (journal entries)
fortnox_get_voucher - Get voucher details with rows
fortnox_create_voucher - Create manual voucher
fortnox_list_voucher_series - List available voucher series

Installation

Via npx (Recommended)

No installation needed! Just add the config above to Claude Desktop.

Manual Installation

npm install -g fortnox-mcp-server

From Source

git clone https://github.com/jakobwennberg/fortnox-mcp.git
cd fortnox-mcp
npm install
npm run build

Configuration

Environment Variables

Variable	Required	Description
`FORTNOX_CLIENT_ID`	Yes	Your Fortnox app client ID
`FORTNOX_CLIENT_SECRET`	Yes	Your Fortnox app client secret
`FORTNOX_REFRESH_TOKEN`	Yes	OAuth2 refresh token
`FORTNOX_ACCESS_TOKEN`	No	Current access token (auto-refreshed)
`TRANSPORT`	No	`stdio` (default) or `http`
`PORT`	No	HTTP port (default: 3000)

Getting OAuth Credentials

Register as a developer at Fortnox Developer Portal
Create a new application to get Client ID and Client Secret
Complete the OAuth2 authorization flow to obtain a refresh token
Set the environment variables

Usage

With Claude Desktop

See Quick Start above.

As HTTP Server

TRANSPORT=http PORT=3000 node dist/index.js

Then connect to http://localhost:3000/mcp

Tool Examples

List Unpaid Invoices

{
  "tool": "fortnox_list_invoices",
  "arguments": {
    "filter": "unpaid",
    "limit": 20
  }
}

Create Invoice

{
  "tool": "fortnox_create_invoice",
  "arguments": {
    "customer_number": "1001",
    "rows": [
      {
        "description": "Consulting services",
        "quantity": 10,
        "price": 1000
      }
    ]
  }
}

Create Voucher

{
  "tool": "fortnox_create_voucher",
  "arguments": {
    "voucher_series": "A",
    "description": "Office supplies",
    "transaction_date": "2025-01-24",
    "rows": [
      { "account_number": 6110, "debit": 500 },
      { "account_number": 1910, "credit": 500 }
    ]
  }
}

Rate Limiting

The Fortnox API allows 25 requests per 5 seconds. This server includes automatic rate limiting to prevent exceeding this limit.

Development

# Run in development mode with auto-reload
npm run dev

# Build for production
npm run build

# Clean build artifacts
npm run clean

Publishing & Distribution

This server is published to multiple registries for easy installation:

Registry	URL	Purpose
npm	npmjs.com/package/fortnox-mcp-server	Package distribution via `npx`
MCP Registry	registry.modelcontextprotocol.io	Official MCP server discovery
GitHub	github.com/jakobwennberg/fortnox-mcp	Source code

How It Works

User adds config to Claude Desktop with npx fortnox-mcp-server
Claude Desktop starts the server via npx (downloads latest version from npm)
Server authenticates with Fortnox using OAuth2 credentials from environment variables
Claude can now use tools like fortnox_list_invoices, fortnox_create_customer, etc.
Server handles API calls to Fortnox, including automatic token refresh and rate limiting

Releasing New Versions

To release a new version, use the release script:

# Bug fixes (1.0.0 → 1.0.1)
npm run release:patch

# New features (1.0.0 → 1.1.0)
npm run release:minor

# Breaking changes (1.0.0 → 2.0.0)
npm run release:major

The release script automatically:

Bumps the version in package.json
Updates server.json for the MCP Registry
Builds the project
Commits and tags the release
Publishes to npm
Publishes to MCP Registry
Pushes to GitHub

Prerequisites for releasing:

npm login - Logged into npm
mcp-publisher login github - Logged into MCP Registry
Clean git working directory

Users Get Updates Automatically

When you publish a new version, users running npx -y fortnox-mcp-server will automatically get the latest version the next time they restart Claude Desktop.

License

MIT

fortnox

Quick Install