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Fortnox API and MCP server

Fortnox's API is gated: it takes a registered integration and a licence for each resource, and it has no action to send an invoice to the customer. Sign in to Fortnox once in your own Cloud Browser, and your AI agent does the work there for you. The same tools work over MCP for agents and as a REST API for scripts.

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Not affiliated with Fortnox.

Fortnox has no API for this. So we run one for you.

Fortnox's own API, a GitHub MCP server and Cotlet compared
What you need Fortnox's APIGitHub MCP serverCotlet
Sending invoices No Partly Yes, 11 tools
Acts as you, signed in 24/7 No No Yes, Cloud Browser
Fixed for you when Fortnox changes N/A No Yes, tested every 6h
Runs with your laptop off N/A No Yes, hosted

Checked Oct 14, 2026. Sources: Fortnox Developer: Scopes · Fortnox Developer: Vouchers · Fortnox Developer: Build and publish an integration · Fortnox on Zapier: triggers and actions

Your own Cloud Browser, on 24/7. Sign in once. We keep it connected.

  1. 01Sign in to Fortnox in your own Cloud Browser

  2. 02Connect it for your agents

  3. 03Cotlet keeps it signed in and working

How do I connect Fortnox to Claude, ChatGPT or my code?

AI agents connect over MCP, scripts call the REST API. Both reach the same 11 tools with one API key.

For AI agents: MCP

Add Cotlet to your agent once. Fortnox and every other app you connect show up as its tools.

  • Claude
  • ChatGPT
  • OpenClaw
  • Hermes
  • GrokBot
  • Cursor
  • n8n
  • Any MCP client
  1. 1

    Add Cotlet to your agent

    Claude Code
    claude mcp add --transport http cotlet \
  https://cotlet.dev/mcp/v1 \
  --header "Authorization: Bearer $COTLET_API_KEY"
    Cursor
    {
  "mcpServers": {
    "cotlet": {
      "url": "https://cotlet.dev/mcp/v1",
      "headers": {
        "Authorization": "Bearer ${COTLET_API_KEY}"
      }
    }
  }
}
    Codex
    # ~/.codex/config.toml
[mcp_servers.cotlet]
url = "https://cotlet.dev/mcp/v1"
bearer_token_env_var = "COTLET_API_KEY"

    Paste the snippet for your client. The same server and key serve every app you connect, so you do this once.

For scripts: REST API

Every tool is an endpoint under /api/v1/fortnox with its own method and path, such as POST /api/v1/fortnox/customers/{customer_number}/invoices, with the same API key. Our open-source repo has ready scripts to start from.

REST API docs

What can the Fortnox API and MCP server do?

11 tools on your own Fortnox account. Agents call them as operations of the MCP tools fortnox_read and fortnox_write; scripts call each one at its own REST endpoint, with the same inputs and answers.

API reference
Fortnox tools in Cotlet's MCP server and REST API
Tool What it does Access
list_customers Customers in the customer register with number, name, organisation number and email. read
list_invoices Customer invoices with number, customer, dates, total and remaining balance. read
get_invoice One invoice with its rows, totals, booked state and payments. read
list_vouchers Vouchers in a voucher series and date range with description and total. read
list_financial_years Financial years that exist in the company, with start and end dates. read
create_customer Add a customer to the customer register with name, email and organisation number. write
create_invoice Save a customer invoice with dates and rows. It is saved, not booked and not sent. writeasks first
bookkeep_invoice Book a saved invoice. A booked invoice can no longer be changed. writeasks first
send_invoice Send a booked invoice to the customer by email, e-invoice or print service. writeasks first
register_payment Register a received payment, full or partial, against a customer invoice. writeasks first
create_voucher Book a voucher with rows of account, debit and credit in a voucher series. writeasks first

Scroll the table for all 11 tools.

Ask in plain words. Your agent does the rest.

All Fortnox use cases

Is it safe to connect Fortnox?

You sign in yourself in your own Cloud Browser, we never save your password, and anything that reaches your readers waits for your OK. The browser profile is encrypted in the EU. Independent scanners grade cotlet.dev A+.

Security overview

How much do the Fortnox API and MCP server cost?

One price for both: a tool call costs the same over MCP or REST. Free 7-day trial with 2,000 credits, no card needed. Then one-time credit packs, no subscription, valid 12 months. Each call uses 10 credits, and your Cloud Browser uses 50 credits a day while Fortnox is enabled for agents, so 20 calls a day come to 250 credits.

See full pricing
Cotlet credit packs: price, credits and calls at 10 credits each
Credits Price, one time Calls at 10 credits Per 1,000 credits
5,000 $29 500 $5.80
15,000 $79 1,500 $5.27
32,000 $149 3,200 $4.66
60,000 $249 6,000 $4.15

Only successful calls use credits; failed calls and timeouts cost nothing. At a balance of 0 calls pause, never a surprise charge. Authenticate with the Authorization: Bearer header.

Questions

Does Fortnox have an API?

Yes, Fortnox has a public REST API with scopes for invoices, customers, vouchers and invoice payments (checked 14 Oct 2026), but it is not open by default: you register an integration, request scopes, and the company must hold the Fortnox licence each resource needs. Fortnox publishes no MCP server of its own.

How do I get access?

Sign up free, open Fortnox under Integrations in the console and press Request access. Your free trial starts with your account, no card needed.

Is the MCP server different from the API?

No, only the way in. Cotlet builds each integration as a REST API and puts an MCP server on top, so both have the same 11 tools, the same inputs and answers, one API key and one price. AI agents such as Claude, ChatGPT or Cursor use MCP; scripts, cron jobs and HTTP steps in n8n, Make or Zapier use the REST API.

What is the Cloud Browser?

Your own Chrome that Cotlet runs for you in the EU, around the clock. You open it from the console, sign in to Fortnox yourself and press Enable for agents. Your agent's calls go through it, from its IP with its cookies, so Fortnox sees the browser you signed in with. Password saving is off and the profile is stored encrypted with AES-256-GCM.

Can my agent act without asking me?

Not on anything that reaches other people: create_invoice, bookkeep_invoice, send_invoice, register_payment, create_voucher wait for your OK by default. You can switch that off per tool for scheduled runs.

Which Fortnox licence does my company need?

Cotlet works in your own Fortnox account, so you need the access your user already has: Fakturering for invoices and payments, Bokföring for vouchers. For comparison, the official API ties each scope to a licence, for example invoice to Order or Kundfaktura and bookkeeping to Bokföring or Kundfaktura.

Should I use a Fortnox MCP server from GitHub instead?

Pick one if you want the code on your own computer and do not mind the upkeep: you install it, sign it in and fix it when Fortnox changes. Pick Cotlet if you want it hosted and kept working for you.

Can I use it in n8n, Make or Zapier?

Yes. Add https://cotlet.dev/mcp/v1 in n8n's MCP Client node, or call the REST endpoints from an HTTP step in Make or Zapier.

Who runs Cotlet?

Cotlet is run by Take Group, a Polish software company working since 2019. Take Group runs about 3,200 websites on its own systems and has its own DevOps team for infrastructure security. We built and used integrations like this inside the company for years before opening them as Cotlet.

Is Cotlet affiliated with Fortnox?

No. Cotlet is independent and not affiliated with Fortnox.

Give your agent access to Fortnox.

Free 7-day trial with 2,000 credits, no card needed.

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