Getting started

Install

dotnet add package Tharga.Fortnox

Register

builder.Services.AddThargaFortnox();

Configure

By code:

builder.Services.AddThargaFortnox(o =>
{
    o.ClientId = "<Your Fortnox Client Id>";
    o.ClientSecret = "<Your Fortnox Client Secret>";
    o.RedirectUri = new Uri("https://your-app/fortnox/connect");
});

Or via appsettings.json:

{
  "Fortnox": {
    "ClientId": "<Your Fortnox Client Id>",
    "ClientSecret": "<Your Fortnox Client Secret>",
    "RedirectUri": "https://your-app/fortnox/connect"
  }
}

Configuration is resolved lazily — values are read on first use, so missing keys surface as an InvalidOperationException only when you actually try to build a connect URI or refresh a token.

What gets registered

AddThargaFortnox registers two services:

Service	Lifetime	Purpose
IFortnoxConnectionService	Transient	Builds connect URIs, exchanges authorization codes for tokens, refreshes/revokes tokens. See Connection flow.
IFortnoxTokenManager	Singleton	Caches and proactively refreshes access tokens per key. See Token manager.

Both share the same Options and HttpClient factory entry, so configuration applies uniformly.

Next

• Connection flow — get a user-authorized token for the first time
• Token manager — keep using that token across calls without manually checking expiry
• Scopes — pick the right FortnoxScope flags for what your app needs