Integrate Fortnox with just a few lines of code. Our unified Accounting API normalizes data across 200+ integrations, so you write once and connect everywhere.

Normalized responses — same data structure for all accounting apps
Official SDKs — Node.js, Python, and more with TypeScript support
Full documentation — interactive API reference with Fortnox-specific examples

View Fortnox API documentation →

import { Apideck } from '@apideck/node'

const apideck = new Apideck({
 apiKey: process.env.APIDECK_API_KEY,
 appId: process.env.APIDECK_APP_ID,
 consumerId: 'user-123'
})

// List invoices from Fortnox
const { data } = await apideck.accounting.invoicesAll({
 serviceId: 'fortnox'
})

console.log(`Found ${data.length} invoices`)

Explore all SDKs ↓

Why integrate Fortnox with Apideck?

Build a production-ready Fortnox integration with enterprise-grade reliability

Ship Fortnox integration fast

Go live with Fortnox in days, not months. Our unified Accounting API handles authentication, data normalization, and error handling so your team can focus on building features.

16+ Fortnox data models

Access 16+ data models for Fortnox including invoices, customers and bills. Read and write data through a single standardized API.

Real-time webhook coverage

Keep your product synchronized with Fortnox using webhooks. Receive push updates for invoices, customers, payments, and more without polling.

Get started for free

API Resources

Push and pull Fortnox data

Use our Unify API to get real-time data from Fortnox

Accounts

Accounting API

Tax Rates

Accounting API

Invoices

Accounting API

Customers

Accounting API

Supplier Invoices

Accounting API

Suppliers

Accounting API

Articles

Accounting API

Invoice Payments

Accounting API

Invoices Credit

Accounting API

Vouchers

Accounting API

Purchase Orders

Accounting API

Attachments

Accounting API

Projects

Accounting API

Supplier Invoice Payments

Accounting API

Accounts Bank

Accounting API

View API Reference

Technical Specifications

Fortnox API integration details

Everything you need to know about integrating Fortnox through our unified Accounting API.

Authentication

OAuth 2.0

Secure token-based authentication

Data Models

16+ resources

Access 16+ normalized data models

Webhooks

Virtual webhooks

Real-time data sync on changes

Security

SOC 2 Type II

Enterprise-grade security certified

Token Management

Automatic refresh

Never worry about expired tokens

API Format

REST + JSON

Standard REST API with JSON responses

Fortnox direct API vs Apideck unified API

Feature	Direct Fortnox API	Apideck Unified API
OAuth implementation	Build from scratch	Handled by Vault
Token refresh	Manual handling	Automatic
Data normalization	Fortnox format only	Normalized across 200+ apps
Error handling	Platform-specific	Unified error codes
Rate limit management	DIY implementation	Built-in throttling
Maintenance	Ongoing updates required	We handle API changes
Additional integrations	Separate work each	Same code, 200+ apps

View complete Fortnox API reference →

Use Cases

What integrations can you build with Fortnox?

Power these accounting workflows with Fortnox data through our unified API.

Accounts Payable

Sync vendor bills, approvals & payments across accounting systems in real time.

Learn more

Accounts Receivable

Push invoices, payment statuses & credits into users' ledgers.

Learn more

Payroll Accounting

Streamline payroll data flow between HR systems and accounting platforms seamlessly.

Learn more

Procurement

Automate purchase orders, vendor management, and spend tracking across ERP and accounting systems.

Learn more

Tax Automation

Connect to accounting data to accurately calculate, file, and reconcile sales tax.

Learn more

View all use cases

Fortnox Integration FAQ

Common questions about integrating Fortnox with your application

Learn more about Fortnox

Discover insights, developer guides, and best practices for working with Fortnox integrations.

👁 How to Integrate with the Fortnox API

How to Integrate with the Fortnox API

Complete guide to Fortnox API integration: OAuth 2.0 auth, invoice and payment endpoints with code examples, pagination, rate limits, and webhooks.

👁 Kateryna Poryvay

Kateryna Poryvay

May 1, 2026

👁 Fortnox OAuth Credentials Guide

Setup GuideOAuth Guide

Fortnox OAuth Credentials Guide

Step-by-step guide to set up oauth credentials for your Fortnox integration.

👁 Apideck Docs

Apideck Docs

Developer Guide

View all articles View developer guides

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