Comparison · open sourceHosted or open-source
Fortnox MCP server?
There are open-source Fortnox MCP servers on GitHub. We read the README and metadata of what can be found and compare it with Nordsynk: what you host yourself, what is not stated and what it costs.
Last checked: 12 October 2026
Nordsynk sells one of the options. The details about the projects come from GitHub, and where a README is silent we write Not stated.
Two ways to start · example taken from the README
Own server · local mode
{
"mcpServers": {
"fortnox": {
"command": "npx",
"args": ["-y", "fortnox-mcp-server"],
"env": {
"FORTNOX_CLIENT_ID": "…",
"FORTNOX_CLIENT_SECRET": "…",
"FORTNOX_REFRESH_TOKEN": "…"
}
}
}
}You fetch the client ID, secret and refresh token yourself from an app you have registered in the Fortnox developer portal.
Nordsynk
- 01Activate Nordsynk for the company in Fortnox
- 02Each user connects their AI assistant and signs in to Nordsynk by email
- 03Approve changes in the browser
Quick comparison
The comparison covers erp-mafia/fortnox-mcp, the project with the most activity of those we found. Other projects may differ.
- Source code
Open source
Open. MIT licence, so you can read and change the code.
Nordsynk
A hosted service from Nordbeam AB.
- Hosting
Open source
A local mode through npx, or a remote mode that you deploy yourself. The README shows Vercel and Upstash Redis as examples.
Nordsynk
Hosted by Nordbeam AB on Cloudflare Workers.
- Fortnox app
Open source
You register an app of your own in the Fortnox developer portal and fetch a client ID and secret.
Nordsynk
Activated in Fortnox. No app of your own is needed.
- Token storage
Open source
Locally the refresh token is saved in a file with 0600 permissions. Remote mode uses Redis, or memory, which the README does not recommend in production.
Nordsynk
Fortnox tokens are stored encrypted and renewed per user and company.
- Approval before changes
Open source
Not stated. The README lists write actions such as create, update, delete and bookkeep, but describes no confirmation step.
Nordsynk
A preview in the browser by default. An administrator can choose auto-approve per company, or read-only.
- Multiple companies
Open source
Not stated. Remote mode is described as multi-user.
Nordsynk
Activated per company. A user needs a seat in every company.
- Tools
Open source
51 tools in the README, including customers, invoices, supplier invoices, vouchers and analytics reports.
Nordsynk
The whole Fortnox API (377 operations) plus ready-made workflows.
- Price
Open source
No software fee. You pay for your own hosting.
Nordsynk
199 SEK per Fortnox company and user per month through Fortnox.
- Support
Open source
GitHub. The README states no support level.
Nordsynk
Email support, in Swedish and English.
Sources, read 12 October 2026: The GitHub repo, README, Nordsynk's Fortnox listing.
What is on GitHub
We searched GitHub for fortnox mcp on 12 October 2026 and read the README and metadata of each hit. The search shows only a selection, so there may be more projects.
Source · GitHub, 12 October 2026
Hits for fortnox mcp
| Project | Licence | Stars | Last changed | README describes |
|---|---|---|---|---|
| erp-mafia/fortnox-mcp | LicenceMIT | Stars40 | Last changed28 Apr 2026 | README describesAn MCP server with 51 tools |
| itzaks/fortnox-mcp | LicenceMIT | Stars0 | Last changed9 Mar 2026 | README describesStarts the same as the erp-mafia README |
| noahboekelman/fortnox-mcp-wrapper-typescript | LicenceApache-2.0 | Stars0 | Last changed5 Feb 2026 | README describesA TypeScript library, not an MCP server |
| wallmander-app/fortnox-mcp-server | LicenceNone stated | Stars0 | Last changed11 Aug 2026 | README describesNo README |
| Proviscale/fortnox-mcp-server | Licence– | Stars– | Last changed– | README describesThe address returns 404 |
A project that has not changed in a few months is not necessarily abandoned, but check that it follows Fortnox API changes before you rely on it.
What a server of your own looks like
The README describes two modes. Local mode is started by Claude Desktop with your own Fortnox credentials. Remote mode needs a public address of your own and a database for tokens.
What is required · according to the erp-mafia/fortnox-mcp README
Environment variables per mode
| Variable | Mode | Required |
|---|---|---|
| FORTNOX_CLIENT_ID | ModeLocal and remote | RequiredYes |
| FORTNOX_CLIENT_SECRET | ModeLocal and remote | RequiredYes |
| FORTNOX_REFRESH_TOKEN | ModeLocal | RequiredYes, on first start |
| AUTH_MODE=remote | ModeRemote | RequiredYes |
| SERVER_URL | ModeRemote | RequiredYes |
| JWT_SECRET | ModeRemote | RequiredYes |
| UPSTASH_REDIS_REST_URL and _TOKEN | ModeRemote | RequiredYes, otherwise memory |
Who does what
What you take on with a server of your own
- 01Register an app of your own in the Fortnox developer portal and fetch a client ID and secret.
- 02Complete the OAuth flow yourself to get a refresh token in local mode.
- 03Store tokens. According to the README, Fortnox refresh tokens can be used only once, so the latest one must be saved after every renewal.
- 04Deploy and keep remote mode running, with a JWT secret and a Redis database for tokens.
- 05Keep the code up to date. Through npx the latest version is fetched on restart, and a deployment of your own you update yourself.
- 06Decide yourself how write actions are protected, since the README describes no approval step.
What Nordsynk handles for you
- 01Activation in Fortnox, with no app of your own and no client secret to store.
- 02Encrypted storage and renewal of Fortnox tokens per user and company.
- 03A preview in the browser before every change, unless you have chosen auto-approve for the company.
- 04Ready-made workflows for supplier invoices, OCR rows, approval and SIE export.
- 05Hosting and updates at Nordbeam AB. You touch no server.
- 06Email support, in Swedish and English.
When open source fits better
You are a developer with infrastructure of your own and want to read or change the code. Then the project costs nothing, and you decide which tools are exposed.
You are building a side project that only reads, such as an alert for new customer invoices. Then you need neither approvals nor multiple users, just a token and a scheduled job.
You can also start from an open project and build on it. Expect to be responsible for hosting, updates and security yourself.
Frequently asked questions about open-source Fortnox MCP
Is there an open-source Fortnox MCP server?
Yes. On 12 October 2026 we found erp-mafia/fortnox-mcp, which is MIT-licensed, has 40 stars on GitHub and was last changed on 28 April 2026. The other hits had a README that starts the same way, were a library that is not an MCP server, or had no README. The search shows only a selection.
How do I run a Fortnox MCP server locally?
According to the README for erp-mafia/fortnox-mcp you register an app in the Fortnox developer portal, fetch a client ID and secret and complete OAuth to get a refresh token. Then you add the server to Claude Desktop with npx and the three values as environment variables.
Can I switch from open source to Nordsynk?
Yes. You activate Nordsynk in Fortnox and add the new connection to your AI client. The bookkeeping stays in Fortnox whichever server you use, so there is nothing to move. Remove the old server from the client and revoke your own Fortnox app if you no longer use it.
Is Nordsynk built on an open-source server?
No. Nordsynk is an implementation of its own from Nordbeam AB against Fortnox's public API, and it is not built on any of the projects mentioned here.
What happens to my tokens in Nordsynk?
Fortnox tokens are stored encrypted and renewed per user and Fortnox company. You never handle a client secret or a token file yourself.
Do open-source servers require approval before anything changes in Fortnox?
It is not stated in the README for erp-mafia/fortnox-mcp, which lists write actions but no confirmation step. That does not mean it is missing in the code, so read it before you let an AI client change your books. Nordsynk shows every change as a preview in the browser.