openapi: 3.0.3
info:
  title: Quaderno Authentication Checkout 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: Checkout
  description: Hosted checkout sessions for collecting tax-compliant payments.
paths:
  /checkout/sessions.json:
    post:
      operationId: createCheckoutSession
      tags:
      - Checkout
      summary: Create a checkout session
      description: Creates a hosted checkout session for collecting a tax-compliant payment. The session can be rendered with Quaderno.js or redirected to a hosted checkout page.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CheckoutSessionInput'
      responses:
        '201':
          description: The created checkout session.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CheckoutSession'
        '422':
          $ref: '#/components/responses/ValidationError'
  /checkout/sessions/{id}.json:
    parameters:
    - $ref: '#/components/parameters/Id'
    get:
      operationId: getCheckoutSession
      tags:
      - Checkout
      summary: Retrieve a checkout session
      responses:
        '200':
          description: The requested checkout session.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CheckoutSession'
        '404':
          $ref: '#/components/responses/NotFound'
components:
  schemas:
    CheckoutSession:
      allOf:
      - $ref: '#/components/schemas/CheckoutSessionInput'
      - type: object
        properties:
          id:
            type: string
          url:
            type: string
          status:
            type: string
    CheckoutSessionInput:
      type: object
      properties:
        success_url:
          type: string
        cancel_url:
          type: string
        currency:
          type: string
        customer:
          $ref: '#/components/schemas/ContactInput'
        items:
          type: array
          items:
            type: object
            properties:
              description:
                type: string
              quantity:
                type: number
              unit_price:
                type: number
              tax_code:
                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
    Error:
      type: object
      properties:
        error:
          type: string
        errors:
          type: object
          additionalProperties: true
  parameters:
    Id:
      name: id
      in: path
      required: true
      description: The unique ID of the resource.
      schema:
        type: string
  responses:
    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'
  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.