Fortnox

Fortnox is a Swedish cloud accounting, ERP, and business-administration platform for small and medium-sized businesses and accounting bureaus. Its REST API at https://api.fortnox.se/3/ programmatically manages accounting and financial data - invoices, customers, articles, orders, offers, vouchers, accounts, suppliers, supplier invoices, projects, and financial years - authenticated with OAuth2 Authorization Code Flow. Fortnox also publishes a duplex WebSocket event stream at wss://ws.fortnox.se/topics-v1 that pushes minimal change notifications across domains so integrations can react to changes instead of polling.

Fortnox publishes 12 APIs on the APIs.io network, including Topics WebSocket API, Accounts API, Articles API, and 9 more. Tagged areas include Accounting, ERP, Invoicing, Bookkeeping, and Sweden.

The Fortnox catalog on APIs.io includes 1 event-driven AsyncAPI specification and 1 Spectral governance ruleset.

Fortnox’s developer surface includes authentication, documentation, engineering blog, and 7 more developer resources.

🌐 Visit website 📡 Source on GitHub

41.5/100 thin ▬ flat Agent 32/100 agent aware Full breakdown ↓
scored 2026-08-03 · rubric v0.9

AccessFreemiumSelf serve⚡ Free to try

12 APIs

AccountingERPInvoicingBookkeepingSwedenNordicsFinanceVouchersCustomersSaaS

Kin Score

Kin Score How this is scored →
scored 2026-08-03 · rubric v0.9

Composite quality — 41.5/100 · thin

Contract Quality 15.8 / 25

Developer Ergonomics 4.3 / 20

Commercial Clarity 7.9 / 20

Operational Transparency 2.7 / 13

Governance 3.3 / 12

Discoverability 7.4 / 10

Agent readiness — 32/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 6 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/fortnox: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

APIs 12

Individual APIs this provider publishes, each with its own machine-readable definition.

Fortnox Topics WebSocket API

Duplex WebSocket stream at wss://ws.fortnox.se/topics-v1 that pushes minimal change-notification events across domains (invoices, supplier-invoices, customers, articles, orders,...

Fortnox Accounts API

Chart of accounts.

Fortnox Articles API

Article (product/service) register.

Fortnox Customers API

Customer register.

Fortnox Financial Years API

Financial (accounting) years.

Fortnox Invoices API

Accounts-receivable customer invoices.

Fortnox Offers API

Offers (quotations).

Fortnox Orders API

Sales orders.

Fortnox Projects API

Projects for tagging and reporting.

Fortnox Supplier Invoices API

Inbound accounts-payable supplier invoices.

Fortnox Suppliers API

Supplier register.

Fortnox Vouchers API

Accounting vouchers (journal entries).

Scroll for all 12

Open Collections 1

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

Fortnox REST API

OPEN COLLECTION

Pricing Plans 1

Published pricing tiers and plan structures.

Fortnox Plans Pricing

6 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Fortnox Rate Limits

2 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Fortnox Finops

FINOPS

Event Specifications 1

AsyncAPI definitions for this provider's event-driven and streaming APIs.

Fortnox Topics WebSocket API

AsyncAPI 2.6 description of Fortnox's **real duplex WebSocket API** at `wss://ws.fortnox.se/topics-v1` (the "Topics" service). Unlike the REST API at https://api.fortnox.se/3/, ...

ASYNCAPI

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

Fortnox API Rules

3 rules · 1 errors 1 warnings 1 info

SPECTRAL

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Fortnox Authentication

oauth2/apiKey · 3 schemes

SECURITY

Fortnox Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Fortnox Agentic Access

42 operations · 21 acting

AGENTIC

Resources

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Authentication

Authentication

Operate 1

Status, limits, changes, and where to get help

RateLimits

RateLimits

Commercial 2

Pricing, plans, and the legal terms of use

Plans

Plans

FinOps

FinOps

Company 3

The organization behind the API

LinkedIn

Website

Website

Blog

Blog

Source (apis.yml)

aid: fortnox
url: https://raw.githubusercontent.com/api-evangelist/fortnox/refs/heads/main/apis.yml
name: Fortnox
kind: company
description: Fortnox is a Swedish cloud accounting, ERP, and business-administration platform for small and medium-sized businesses
  and accounting bureaus. Its REST API at https://api.fortnox.se/3/ programmatically manages accounting and financial data
  - invoices, customers, articles, orders, offers, vouchers, accounts, suppliers, supplier invoices, projects, and financial
  years - authenticated with OAuth2 Authorization Code Flow. Fortnox also publishes a duplex WebSocket event stream at wss://ws.fortnox.se/topics-v1
  that pushes minimal change notifications across domains so integrations can react to changes instead of polling.
accessModel:
  pricing: freemium
  onboarding: self-serve
  trial: false
  try_now: true
  public: false
  label: Freemium · Self-serve signup
  confidence: high
  source:
  - plans
  - authentication
  generated: '2026-07-22'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/fortnox.png
tags:
- Accounting
- ERP
- Invoicing
- Bookkeeping
- Sweden
- Nordics
- Finance
- Vouchers
- Customers
- SaaS
created: '2026-07-12'
modified: '2026-07-12'
specificationVersion: '0.19'
apis:
- aid: fortnox:fortnox-topics-websocket-api
  name: Fortnox Topics WebSocket API
  tags:
  - WebSocket
  - Events
  - Change Notifications
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  humanURL: https://www.fortnox.se/developer/guides-and-good-to-know/websockets
  baseURL: wss://ws.fortnox.se/topics-v1
  properties:
  - url: https://www.fortnox.se/developer/guides-and-good-to-know/websockets
    type: Documentation
  - url: asyncapi/fortnox-asyncapi.yml
    type: AsyncAPI
  description: Duplex WebSocket stream at wss://ws.fortnox.se/topics-v1 that pushes minimal change-notification events across
    domains (invoices, supplier-invoices, customers, articles, orders, offers, vouchers, projects, and more) so integrations
    react to changes instead of polling the REST API. Kafka-backed, at-least-once delivery, with per-topic offsets and up
    to 14-day replay.
- aid: fortnox:fortnox-accounts-api
  name: Fortnox Accounts API
  description: Chart of accounts.
  humanURL: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  baseURL: https://api.fortnox.se/3
  tags:
  - Accounts
  properties:
  - type: OpenAPI
    url: openapi/fortnox-accounts-api-openapi.yml
  - type: Documentation
    url: https://www.fortnox.se/developer
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  - type: PostmanCollection
    url: collections/fortnox.postman_collection.json
  - type: OpenCollection
    url: collections/fortnox.opencollection.json
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/customers/customers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/articles/articles
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/order/orders
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/offer/offers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/vouchers/vouchers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/suppliers/suppliers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/projects/projects
- aid: fortnox:fortnox-articles-api
  name: Fortnox Articles API
  description: Article (product/service) register.
  humanURL: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  baseURL: https://api.fortnox.se/3
  tags:
  - Articles
  properties:
  - type: OpenAPI
    url: openapi/fortnox-articles-api-openapi.yml
  - type: Documentation
    url: https://www.fortnox.se/developer
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  - type: PostmanCollection
    url: collections/fortnox.postman_collection.json
  - type: OpenCollection
    url: collections/fortnox.opencollection.json
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/customers/customers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/articles/articles
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/order/orders
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/offer/offers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/vouchers/vouchers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/suppliers/suppliers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/projects/projects
- aid: fortnox:fortnox-customers-api
  name: Fortnox Customers API
  description: Customer register.
  humanURL: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  baseURL: https://api.fortnox.se/3
  tags:
  - Customers
  properties:
  - type: OpenAPI
    url: openapi/fortnox-customers-api-openapi.yml
  - type: Documentation
    url: https://www.fortnox.se/developer
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  - type: PostmanCollection
    url: collections/fortnox.postman_collection.json
  - type: OpenCollection
    url: collections/fortnox.opencollection.json
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/customers/customers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/articles/articles
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/order/orders
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/offer/offers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/vouchers/vouchers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/suppliers/suppliers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/projects/projects
- aid: fortnox:fortnox-financial-years-api
  name: Fortnox Financial Years API
  description: Financial (accounting) years.
  humanURL: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  baseURL: https://api.fortnox.se/3
  tags:
  - Financial Years
  properties:
  - type: OpenAPI
    url: openapi/fortnox-financial-years-api-openapi.yml
  - type: Documentation
    url: https://www.fortnox.se/developer
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  - type: PostmanCollection
    url: collections/fortnox.postman_collection.json
  - type: OpenCollection
    url: collections/fortnox.opencollection.json
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/customers/customers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/articles/articles
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/order/orders
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/offer/offers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/vouchers/vouchers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/suppliers/suppliers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/projects/projects
- aid: fortnox:fortnox-invoices-api
  name: Fortnox Invoices API
  description: Accounts-receivable customer invoices.
  humanURL: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  baseURL: https://api.fortnox.se/3
  tags:
  - Invoices
  properties:
  - type: OpenAPI
    url: openapi/fortnox-invoices-api-openapi.yml
  - type: Documentation
    url: https://www.fortnox.se/developer
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  - type: PostmanCollection
    url: collections/fortnox.postman_collection.json
  - type: OpenCollection
    url: collections/fortnox.opencollection.json
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/customers/customers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/articles/articles
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/order/orders
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/offer/offers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/vouchers/vouchers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/suppliers/suppliers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/projects/projects
- aid: fortnox:fortnox-offers-api
  name: Fortnox Offers API
  description: Offers (quotations).
  humanURL: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  baseURL: https://api.fortnox.se/3
  tags:
  - Offers
  properties:
  - type: OpenAPI
    url: openapi/fortnox-offers-api-openapi.yml
  - type: Documentation
    url: https://www.fortnox.se/developer
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  - type: PostmanCollection
    url: collections/fortnox.postman_collection.json
  - type: OpenCollection
    url: collections/fortnox.opencollection.json
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/customers/customers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/articles/articles
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/order/orders
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/offer/offers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/vouchers/vouchers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/suppliers/suppliers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/projects/projects
- aid: fortnox:fortnox-orders-api
  name: Fortnox Orders API
  description: Sales orders.
  humanURL: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  baseURL: https://api.fortnox.se/3
  tags:
  - Orders
  properties:
  - type: OpenAPI
    url: openapi/fortnox-orders-api-openapi.yml
  - type: Documentation
    url: https://www.fortnox.se/developer
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  - type: PostmanCollection
    url: collections/fortnox.postman_collection.json
  - type: OpenCollection
    url: collections/fortnox.opencollection.json
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/customers/customers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/articles/articles
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/order/orders
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/offer/offers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/vouchers/vouchers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/suppliers/suppliers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/projects/projects
- aid: fortnox:fortnox-projects-api
  name: Fortnox Projects API
  description: Projects for tagging and reporting.
  humanURL: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  baseURL: https://api.fortnox.se/3
  tags:
  - Projects
  properties:
  - type: OpenAPI
    url: openapi/fortnox-projects-api-openapi.yml
  - type: Documentation
    url: https://www.fortnox.se/developer
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  - type: PostmanCollection
    url: collections/fortnox.postman_collection.json
  - type: OpenCollection
    url: collections/fortnox.opencollection.json
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/customers/customers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/articles/articles
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/order/orders
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/offer/offers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/vouchers/vouchers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/suppliers/suppliers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/projects/projects
- aid: fortnox:fortnox-supplier-invoices-api
  name: Fortnox Supplier Invoices API
  description: Inbound accounts-payable supplier invoices.
  humanURL: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  baseURL: https://api.fortnox.se/3
  tags:
  - Supplier Invoices
  properties:
  - type: OpenAPI
    url: openapi/fortnox-supplier-invoices-api-openapi.yml
  - type: Documentation
    url: https://www.fortnox.se/developer
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  - type: PostmanCollection
    url: collections/fortnox.postman_collection.json
  - type: OpenCollection
    url: collections/fortnox.opencollection.json
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/customers/customers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/articles/articles
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/order/orders
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/offer/offers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/vouchers/vouchers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/suppliers/suppliers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/projects/projects
- aid: fortnox:fortnox-suppliers-api
  name: Fortnox Suppliers API
  description: Supplier register.
  humanURL: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  baseURL: https://api.fortnox.se/3
  tags:
  - Suppliers
  properties:
  - type: OpenAPI
    url: openapi/fortnox-suppliers-api-openapi.yml
  - type: Documentation
    url: https://www.fortnox.se/developer
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  - type: PostmanCollection
    url: collections/fortnox.postman_collection.json
  - type: OpenCollection
    url: collections/fortnox.opencollection.json
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/customers/customers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/articles/articles
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/order/orders
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/offer/offers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/vouchers/vouchers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/suppliers/suppliers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/projects/projects
- aid: fortnox:fortnox-vouchers-api
  name: Fortnox Vouchers API
  description: Accounting vouchers (journal entries).
  humanURL: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  baseURL: https://api.fortnox.se/3
  tags:
  - Vouchers
  properties:
  - type: OpenAPI
    url: openapi/fortnox-vouchers-api-openapi.yml
  - type: Documentation
    url: https://www.fortnox.se/developer
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/invoices/invoices
  - type: PostmanCollection
    url: collections/fortnox.postman_collection.json
  - type: OpenCollection
    url: collections/fortnox.opencollection.json
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/customers/customers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/articles/articles
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/order/orders
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/offer/offers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/vouchers/vouchers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/suppliers/suppliers
  - type: APIReference
    url: https://www.fortnox.se/developer/resources-rest-api/projects/projects
common:
- type: AgenticAccess
  url: agentic-access/fortnox-agentic-access.yml
- type: DomainSecurity
  url: security/fortnox-domain-security.yml
- type: Authentication
  url: authentication/fortnox-authentication.yml
- type: LinkedIn
  url: https://www.linkedin.com/company/fortnox-ab
- type: Website
  url: https://www.fortnox.se
- type: Documentation
  url: https://www.fortnox.se/developer
- type: Plans
  url: plans/fortnox-plans-pricing.yml
- type: RateLimits
  url: rate-limits/fortnox-rate-limits.yml
- type: FinOps
  url: finops/fortnox-finops.yml
- url: https://www.fortnox.se/developer/blog
  type: Blog
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

Where this information came from

This is an independent, third-party profile of Fortnox, published by API Evangelist. We do not operate, host, resell, or support these APIs, and we are not affiliated with or endorsed by the company unless stated above. Everything here is built from publicly available information — the company's own site, developer portal, documentation, public repositories, and the specifications it publishes for public use. Nothing is obtained by breaching a system, defeating an access control, or using credentials.

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