Quaderno Transactions API

openapi: 3.2.0
info:
  title: Quaderno Authentication Transactions 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: Transactions
  description: Unified sales transactions that both record a sale and calculate tax.
paths:
  /transactions.json:
    post:
      operationId: createTransaction
      tags:
      - Transactions
      summary: Create a sales transaction
      description: Records a sale and its tax in a single call. Quaderno determines the applicable tax from the customer's location evidence and the item tax codes, then creates the corresponding document.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/TransactionInput'
      responses:
        '201':
          description: The created transaction.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Transaction'
        '422':
          $ref: '#/components/responses/ValidationError'
components:
  schemas:
    Transaction:
      allOf:
      - $ref: '#/components/schemas/TransactionInput'
      - type: object
        properties:
          id:
            type: string
          total:
            type: number
          taxes:
            type: number
    TransactionInput:
      type: object
      required:
      - customer
      - items
      properties:
        customer:
          type: object
          description: Customer identity and location details used for tax determination.
          properties:
            first_name:
              type: string
            last_name:
              type: string
            email:
              type: string
            country:
              type: string
            postal_code:
              type: string
            region:
              type: string
            tax_id:
              type: string
        items:
          type: array
          items:
            type: object
            properties:
              description:
                type: string
              quantity:
                type: number
              unit_price:
                type: number
              tax_code:
                type: string
        payment_method:
          type: string
        evidence:
          type: object
          additionalProperties: true
    Error:
      type: object
      properties:
        error:
          type: string
        errors:
          type: object
          additionalProperties: true
  responses:
    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.