openapi: 3.0.3
info:
  title: Quaderno Authentication Expenses API
  description: 'The Quaderno API is a REST API for tax compliance, invoicing, and sales tax / VAT automation. It exposes resources with predictable, account-scoped URLs and uses standard HTTP features - HTTP Basic Authentication, standard methods, and response codes. All requests and responses are JSON, and every endpoint path ends in `.json` to indicate JSON serialization.

    The base URL is account-scoped: `https://ACCOUNT_NAME.quadernoapp.com/api`, where `ACCOUNT_NAME` is your Quaderno account subdomain. Authenticate with your private API key as the HTTP Basic Auth username (any value for the password). Sandbox testing is available on a separate sandbox host.

    Core resources include Contacts, Items, Invoices, Credits, Estimates, Expenses, Recurring documents, Payments, Transactions, Checkout Sessions, Webhooks, and the tax engine (tax rate calculation, tax jurisdictions, tax codes, and tax ID validation). Endpoint paths and the account-scoped base URL are confirmed against Quaderno''s public developer documentation and the official quaderno-ruby SDK; request and response bodies are modeled and should be verified against the live API reference.'
  version: '1.0'
  contact:
    name: Quaderno
    url: https://developers.quaderno.io
  license:
    name: Proprietary
    url: https://quaderno.io/terms/
servers:
- url: https://{account}.quadernoapp.com/api
  description: Production (account-scoped)
  variables:
    account:
      default: ACCOUNT_NAME
      description: Your Quaderno account subdomain.
security:
- basicAuth: []
tags:
- name: Expenses
  description: Purchases and vendor bills recorded against the account.
paths:
  /expenses.json:
    get:
      operationId: listExpenses
      tags:
      - Expenses
      summary: List expenses
      parameters:
      - $ref: '#/components/parameters/Page'
      responses:
        '200':
          description: A list of expenses.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Expense'
        '401':
          $ref: '#/components/responses/Unauthorized'
    post:
      operationId: createExpense
      tags:
      - Expenses
      summary: Create an expense
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ExpenseInput'
      responses:
        '201':
          description: The created expense.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Expense'
        '422':
          $ref: '#/components/responses/ValidationError'
  /expenses/{id}.json:
    parameters:
    - $ref: '#/components/parameters/Id'
    get:
      operationId: getExpense
      tags:
      - Expenses
      summary: Retrieve an expense
      responses:
        '200':
          description: The requested expense.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Expense'
        '404':
          $ref: '#/components/responses/NotFound'
    put:
      operationId: updateExpense
      tags:
      - Expenses
      summary: Update an expense
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ExpenseInput'
      responses:
        '200':
          description: The updated expense.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Expense'
        '404':
          $ref: '#/components/responses/NotFound'
    delete:
      operationId: deleteExpense
      tags:
      - Expenses
      summary: Delete an expense
      responses:
        '204':
          description: The expense was deleted.
        '404':
          $ref: '#/components/responses/NotFound'
components:
  schemas:
    ExpenseInput:
      type: object
      required:
      - contact_id
      properties:
        contact_id:
          type: string
        contact:
          $ref: '#/components/schemas/ContactInput'
        currency:
          type: string
        payment_method:
          type: string
        items_attributes:
          type: array
          items:
            $ref: '#/components/schemas/DocumentItem'
        notes:
          type: string
    DocumentItem:
      type: object
      description: A line item on a document.
      properties:
        description:
          type: string
        quantity:
          type: number
        unit_price:
          type: number
        discount_rate:
          type: number
        tax_1_name:
          type: string
        tax_1_rate:
          type: number
        tax_code:
          type: string
        reference:
          type: string
    ContactInput:
      type: object
      required:
      - kind
      properties:
        kind:
          type: string
          enum:
          - company
          - person
          description: Whether the contact is a company or a person.
        first_name:
          type: string
        last_name:
          type: string
        contact_name:
          type: string
        street_line_1:
          type: string
        city:
          type: string
        postal_code:
          type: string
        region:
          type: string
        country:
          type: string
          description: ISO 3166-1 alpha-2 country code.
        email:
          type: string
        tax_id:
          type: string
    Expense:
      allOf:
      - $ref: '#/components/schemas/ExpenseInput'
      - type: object
        properties:
          id:
            type: string
          number:
            type: string
          issue_date:
            type: string
          total:
            type: number
    Error:
      type: object
      properties:
        error:
          type: string
        errors:
          type: object
          additionalProperties: true
  responses:
    Unauthorized:
      description: Missing or invalid API key.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    NotFound:
      description: The requested resource was not found.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    ValidationError:
      description: The request payload failed validation.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  parameters:
    Id:
      name: id
      in: path
      required: true
      description: The unique ID of the resource.
      schema:
        type: string
    Page:
      name: page
      in: query
      required: false
      description: Page number for paginated results (25 records per page).
      schema:
        type: integer
        default: 1
  securitySchemes:
    basicAuth:
      type: http
      scheme: basic
      description: HTTP Basic Authentication. Use your private API key as the username; the password can be any value. API keys are managed in the Quaderno account settings.