openapi: 3.0.3
info:
  title: Fortnox REST API (Representative Subset) Accounts Financial Years API
  description: 'Grounded OpenAPI description of the Fortnox REST API - the Swedish cloud accounting/ERP platform for SMBs and accounting bureaus. Base URL is https://api.fortnox.se/3/. Authentication is OAuth2 Authorization Code Flow: each request carries the Access-Token (Bearer JWT, 1h) header plus the Client-Secret header issued to your Fortnox app. The old fixed Access-Token/Client-Secret integration keys were deprecated 2025-04-30.


    SCOPE / FIDELITY NOTE: The Fortnox API exposes 40+ resources. This document ships a solid, representative SUBSET (Invoices, Customers, Articles, Orders, Offers, Vouchers, Accounts, Financial Years, Suppliers, Supplier Invoices, Projects) with pragmatic, partial field-level schemas. Paths, methods, identifiers, the wrapper-object response envelope (e.g. { "Invoice": {...} }, { "Invoices": [...] }), and auth are grounded in Fortnox''s developer documentation. Per-field property coverage is intentionally partial and MODELED/summarized from the docs, not transcribed field-for-field for every resource. Verify exact field sets and validation against https://api.fortnox.se/apidocs before production use.'
  version: '3.0'
  contact:
    name: Fortnox Developer
    url: https://www.fortnox.se/developer
  license:
    name: Fortnox API License / Terms
    url: https://www.fortnox.se/developer
servers:
- url: https://api.fortnox.se/3
  description: Fortnox REST API v3
security:
- accessToken: []
  clientSecret: []
tags:
- name: Financial Years
  description: Financial (accounting) years.
paths:
  /financialyears:
    get:
      operationId: listFinancialYears
      tags:
      - Financial Years
      summary: List financial years
      responses:
        '200':
          description: A list of financial years.
          content:
            application/json:
              schema:
                type: object
                properties:
                  FinancialYears:
                    type: array
                    items:
                      $ref: '#/components/schemas/FinancialYear'
                  MetaInformation:
                    $ref: '#/components/schemas/MetaInformation'
    post:
      operationId: createFinancialYear
      tags:
      - Financial Years
      summary: Create a financial year
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                FinancialYear:
                  $ref: '#/components/schemas/FinancialYear'
      responses:
        '201':
          description: Financial year created.
          content:
            application/json:
              schema:
                type: object
                properties:
                  FinancialYear:
                    $ref: '#/components/schemas/FinancialYear'
components:
  schemas:
    FinancialYear:
      type: object
      description: A financial (accounting) year.
      properties:
        Id:
          type: integer
          readOnly: true
        FromDate:
          type: string
          format: date
        ToDate:
          type: string
          format: date
        AccountingMethod:
          type: string
          enum:
          - ACCRUAL
          - CASH
        accountCharts:
          type: string
      required:
      - FromDate
      - ToDate
    MetaInformation:
      type: object
      description: Pagination metadata returned on list endpoints.
      properties:
        '@TotalResources':
          type: integer
        '@TotalPages':
          type: integer
        '@CurrentPage':
          type: integer
  securitySchemes:
    accessToken:
      type: apiKey
      in: header
      name: Access-Token
      description: OAuth2 Access-Token (Bearer JWT, valid 1 hour) obtained via the Authorization Code Flow from https://apps.fortnox.se/oauth-v1/token. Sent in the Access-Token header on every request.
    clientSecret:
      type: apiKey
      in: header
      name: Client-Secret
      description: The Client-Secret issued to your registered Fortnox developer application. Sent in the Client-Secret header alongside the Access-Token on every request.