Quaderno

Quaderno is a tax compliance, invoicing, and sales-tax / VAT automation platform. Its REST API calculates the correct sales tax, VAT, and GST in real time for any jurisdiction, then issues tax-compliant invoices, credit notes, estimates, and receipts. The account-scoped API (https://ACCOUNT_NAME.quadernoapp.com/api) covers contacts, items, invoices, credits, estimates, expenses, recurring documents, payments, unified sales transactions, hosted Checkout sessions, and webhooks, plus a tax engine for rate calculation, jurisdictions, tax codes, and tax ID validation. Requests use HTTP Basic Auth with a private API key and return JSON; every endpoint path ends in .json.

Quaderno publishes 14 APIs on the APIs.io network, including Authentication API, Checkout API, Contacts API, and 11 more. Tagged areas include Tax Compliance, Sales Tax, VAT, Invoicing, and Billing.

Quaderno’s developer surface includes authentication, documentation, and 8 more developer resources.

🌐 Visit website 📡 Source on GitHub
38.2/100 thin ▬ flat Agent 20/100 agent aware Full breakdown ↓
scored 2026-08-25 · rubric v0.14.0
AccessFreemiumSelf serveFree trial⚡ Free to try
14 APIs
Tax ComplianceSales TaxVATInvoicingBillingFintech

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-08-25 · rubric v0.14.0
Composite quality — 38.2/100 · thin
Contract Quality 14.2 / 25
Developer Ergonomics 4.3 / 20
Access Clarity 7.9 / 20
Operational Transparency 4.4 / 13
Contract Governance 0.0 / 12
Discoverability 7.4 / 10
Agent readiness — 20/100 · agent aware
Machine-Readable Contract 18 / 18
Agentic Access Contract 10 / 10
Documented Reversibility 0 / 6
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 0 / 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
Delegated User Identity 0 / 6
Protected Resource Metadata 0 / 5
Registration Without a Human 0 / 6
Agentic Commerce Surface 0 / 5
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/quaderno: 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 14

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

Quaderno Authentication API

Ping the API and inspect the authenticated account and rate-limit state.

Quaderno Checkout API

Hosted checkout sessions for collecting tax-compliant payments.

Quaderno Contacts API

Customers and vendors.

Quaderno Credits API

Credit notes issued against invoices.

Quaderno Estimates API

Quotes and estimates issued to customers.

Quaderno Evidences API

Location evidence records supporting tax determination for a transaction.

Quaderno Expenses API

Purchases and vendor bills recorded against the account.

Quaderno Invoices API

Sales invoices issued to customers.

Quaderno Items API

Reusable products and services used as document line items.

Quaderno Payments API

Payments recorded against invoices, credits, and expenses.

Quaderno Recurring API

Recurring document templates that auto-generate invoices.

Quaderno Taxes API

Real-time tax rate calculation, jurisdictions, tax codes, and tax ID validation.

Quaderno Transactions API

Unified sales transactions that both record a sale and calculate tax.

Quaderno Webhooks API

Subscriptions that deliver real-time event notifications to your app.

Scroll for all 14

Open Collections 16

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

API Collection

OPEN COLLECTION

Quaderno Authentication API

OPEN COLLECTION

Quaderno Authentication Checkout API

OPEN COLLECTION

Quaderno Authentication Contacts API

OPEN COLLECTION

Quaderno Authentication Credits API

OPEN COLLECTION

Quaderno Authentication Estimates API

OPEN COLLECTION

Quaderno Authentication Evidences API

OPEN COLLECTION

Quaderno Authentication Expenses API

OPEN COLLECTION

Quaderno Authentication Invoices API

OPEN COLLECTION

Quaderno Authentication Items API

OPEN COLLECTION

Quaderno Authentication Payments API

OPEN COLLECTION

Quaderno Authentication Recurring API

OPEN COLLECTION

Quaderno Authentication Taxes API

OPEN COLLECTION

Quaderno Authentication Transactions API

OPEN COLLECTION

Quaderno Authentication Webhooks API

OPEN COLLECTION

Quaderno API

OPEN COLLECTION

Scroll for all 16

Pricing Plans 1

Published pricing tiers and plan structures.

Quaderno Plans Pricing

5 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Quaderno Rate Limits

3 limits

RATE LIMITS

FinOps 1

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

Quaderno Finops

FINOPS

Security Posture 2

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

Quaderno Authentication

http · 1 scheme

SECURITY

Quaderno Domain Security

TLSv1.3 · DMARC

SECURITY

Agentic Access 1

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

Quaderno Agentic Access

53 operations · 28 acting

53 operations · 28 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

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization
GitHubOrganization

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 2

The organization behind the API

LinkedIn
LinkedIn
 Website
Website

Source (apis.yml)

apis.yml Raw ↑ 
aid: quaderno
url: https://raw.githubusercontent.com/api-evangelist/quaderno/refs/heads/main/apis.yml
name: Quaderno
kind: company
description: Quaderno is a tax compliance, invoicing, and sales-tax / VAT automation platform. Its REST API calculates the
  correct sales tax, VAT, and GST in real time for any jurisdiction, then issues tax-compliant invoices, credit notes, estimates,
  and receipts. The account-scoped API (https://ACCOUNT_NAME.quadernoapp.com/api) covers contacts, items, invoices, credits,
  estimates, expenses, recurring documents, payments, unified sales transactions, hosted Checkout sessions, and webhooks,
  plus a tax engine for rate calculation, jurisdictions, tax codes, and tax ID validation. Requests use HTTP Basic Auth with
  a private API key and return JSON; every endpoint path ends in .json.
accessModel:
  pricing: freemium
  onboarding: self-serve
  trial: true
  try_now: true
  public: false
  label: Freemium (free trial) · 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/quaderno.png
tags:
- Tax Compliance
- Sales Tax
- VAT
- Invoicing
- Billing
- Fintech
tags_raw:
- Tax Compliance
- Sales Tax
- VAT
- Invoicing
- Billing
- FinTech
created: '2026-07-03'
modified: '2026-07-03'
specificationVersion: '0.23'
apis:
- aid: quaderno:quaderno-authentication-api
  name: Quaderno Authentication API
  description: Ping the API and inspect the authenticated account and rate-limit state.
  humanURL: https://developers.quaderno.io/api/
  baseURL: https://ACCOUNT_NAME.quadernoapp.com/api
  tags:
  - Authentication
  properties:
  - type: OpenAPI
    url: openapi/quaderno-authentication-api-openapi.yml
  - type: Documentation
    url: https://developers.quaderno.io/api/
  - type: APIReference
    url: https://developers.quaderno.io/api/
  - type: PostmanCollection
    url: collections/quaderno.postman_collection.json
  - type: OpenCollection
    url: collections/quaderno.opencollection.json
  - type: Documentation
    url: https://developers.quaderno.io/guides/checkout/
  - type: Documentation
    url: https://developers.quaderno.io/guides/webhooks/
- aid: quaderno:quaderno-checkout-api
  name: Quaderno Checkout API
  description: Hosted checkout sessions for collecting tax-compliant payments.
  humanURL: https://developers.quaderno.io/api/
  baseURL: https://ACCOUNT_NAME.quadernoapp.com/api
  tags:
  - Checkout
  properties:
  - type: OpenAPI
    url: openapi/quaderno-checkout-api-openapi.yml
  - type: Documentation
    url: https://developers.quaderno.io/api/
  - type: APIReference
    url: https://developers.quaderno.io/api/
  - type: PostmanCollection
    url: collections/quaderno.postman_collection.json
  - type: OpenCollection
    url: collections/quaderno.opencollection.json
  - type: Documentation
    url: https://developers.quaderno.io/guides/checkout/
  - type: Documentation
    url: https://developers.quaderno.io/guides/webhooks/
- aid: quaderno:quaderno-contacts-api
  name: Quaderno Contacts API
  description: Customers and vendors.
  humanURL: https://developers.quaderno.io/api/
  baseURL: https://ACCOUNT_NAME.quadernoapp.com/api
  tags:
  - Contacts
  properties:
  - type: OpenAPI
    url: openapi/quaderno-contacts-api-openapi.yml
  - type: Documentation
    url: https://developers.quaderno.io/api/
  - type: APIReference
    url: https://developers.quaderno.io/api/
  - type: PostmanCollection
    url: collections/quaderno.postman_collection.json
  - type: OpenCollection
    url: collections/quaderno.opencollection.json
  - type: Documentation
    url: https://developers.quaderno.io/guides/checkout/
  - type: Documentation
    url: https://developers.quaderno.io/guides/webhooks/
- aid: quaderno:quaderno-credits-api
  name: Quaderno Credits API
  description: Credit notes issued against invoices.
  humanURL: https://developers.quaderno.io/api/
  baseURL: https://ACCOUNT_NAME.quadernoapp.com/api
  tags:
  - Credits
  properties:
  - type: OpenAPI
    url: openapi/quaderno-credits-api-openapi.yml
  - type: Documentation
    url: https://developers.quaderno.io/api/
  - type: APIReference
    url: https://developers.quaderno.io/api/
  - type: PostmanCollection
    url: collections/quaderno.postman_collection.json
  - type: OpenCollection
    url: collections/quaderno.opencollection.json
  - type: Documentation
    url: https://developers.quaderno.io/guides/checkout/
  - type: Documentation
    url: https://developers.quaderno.io/guides/webhooks/
- aid: quaderno:quaderno-estimates-api
  name: Quaderno Estimates API
  description: Quotes and estimates issued to customers.
  humanURL: https://developers.quaderno.io/api/
  baseURL: https://ACCOUNT_NAME.quadernoapp.com/api
  tags:
  - Estimates
  properties:
  - type: OpenAPI
    url: openapi/quaderno-estimates-api-openapi.yml
  - type: Documentation
    url: https://developers.quaderno.io/api/
  - type: APIReference
    url: https://developers.quaderno.io/api/
  - type: PostmanCollection
    url: collections/quaderno.postman_collection.json
  - type: OpenCollection
    url: collections/quaderno.opencollection.json
  - type: Documentation
    url: https://developers.quaderno.io/guides/checkout/
  - type: Documentation
    url: https://developers.quaderno.io/guides/webhooks/
- aid: quaderno:quaderno-evidences-api
  name: Quaderno Evidences API
  description: Location evidence records supporting tax determination for a transaction.
  humanURL: https://developers.quaderno.io/api/
  baseURL: https://ACCOUNT_NAME.quadernoapp.com/api
  tags:
  - Evidences
  properties:
  - type: OpenAPI
    url: openapi/quaderno-evidences-api-openapi.yml
  - type: Documentation
    url: https://developers.quaderno.io/api/
  - type: APIReference
    url: https://developers.quaderno.io/api/
  - type: PostmanCollection
    url: collections/quaderno.postman_collection.json
  - type: OpenCollection
    url: collections/quaderno.opencollection.json
  - type: Documentation
    url: https://developers.quaderno.io/guides/checkout/
  - type: Documentation
    url: https://developers.quaderno.io/guides/webhooks/
- aid: quaderno:quaderno-expenses-api
  name: Quaderno Expenses API
  description: Purchases and vendor bills recorded against the account.
  humanURL: https://developers.quaderno.io/api/
  baseURL: https://ACCOUNT_NAME.quadernoapp.com/api
  tags:
  - Expenses
  properties:
  - type: OpenAPI
    url: openapi/quaderno-expenses-api-openapi.yml
  - type: Documentation
    url: https://developers.quaderno.io/api/
  - type: APIReference
    url: https://developers.quaderno.io/api/
  - type: PostmanCollection
    url: collections/quaderno.postman_collection.json
  - type: OpenCollection
    url: collections/quaderno.opencollection.json
  - type: Documentation
    url: https://developers.quaderno.io/guides/checkout/
  - type: Documentation
    url: https://developers.quaderno.io/guides/webhooks/
- aid: quaderno:quaderno-invoices-api
  name: Quaderno Invoices API
  description: Sales invoices issued to customers.
  humanURL: https://developers.quaderno.io/api/
  baseURL: https://ACCOUNT_NAME.quadernoapp.com/api
  tags:
  - Invoices
  properties:
  - type: OpenAPI
    url: openapi/quaderno-invoices-api-openapi.yml
  - type: Documentation
    url: https://developers.quaderno.io/api/
  - type: APIReference
    url: https://developers.quaderno.io/api/
  - type: PostmanCollection
    url: collections/quaderno.postman_collection.json
  - type: OpenCollection
    url: collections/quaderno.opencollection.json
  - type: Documentation
    url: https://developers.quaderno.io/guides/checkout/
  - type: Documentation
    url: https://developers.quaderno.io/guides/webhooks/
- aid: quaderno:quaderno-items-api
  name: Quaderno Items API
  description: Reusable products and services used as document line items.
  humanURL: https://developers.quaderno.io/api/
  baseURL: https://ACCOUNT_NAME.quadernoapp.com/api
  tags:
  - Item
  tags_raw:
  - Items
  properties:
  - type: OpenAPI
    url: openapi/quaderno-items-api-openapi.yml
  - type: Documentation
    url: https://developers.quaderno.io/api/
  - type: APIReference
    url: https://developers.quaderno.io/api/
  - type: PostmanCollection
    url: collections/quaderno.postman_collection.json
  - type: OpenCollection
    url: collections/quaderno.opencollection.json
  - type: Documentation
    url: https://developers.quaderno.io/guides/checkout/
  - type: Documentation
    url: https://developers.quaderno.io/guides/webhooks/
- aid: quaderno:quaderno-payments-api
  name: Quaderno Payments API
  description: Payments recorded against invoices, credits, and expenses.
  humanURL: https://developers.quaderno.io/api/
  baseURL: https://ACCOUNT_NAME.quadernoapp.com/api
  tags:
  - Payments
  properties:
  - type: OpenAPI
    url: openapi/quaderno-payments-api-openapi.yml
  - type: Documentation
    url: https://developers.quaderno.io/api/
  - type: APIReference
    url: https://developers.quaderno.io/api/
  - type: PostmanCollection
    url: collections/quaderno.postman_collection.json
  - type: OpenCollection
    url: collections/quaderno.opencollection.json
  - type: Documentation
    url: https://developers.quaderno.io/guides/checkout/
  - type: Documentation
    url: https://developers.quaderno.io/guides/webhooks/
- aid: quaderno:quaderno-recurring-api
  name: Quaderno Recurring API
  description: Recurring document templates that auto-generate invoices.
  humanURL: https://developers.quaderno.io/api/
  baseURL: https://ACCOUNT_NAME.quadernoapp.com/api
  tags:
  - Recurring
  properties:
  - type: OpenAPI
    url: openapi/quaderno-recurring-api-openapi.yml
  - type: Documentation
    url: https://developers.quaderno.io/api/
  - type: APIReference
    url: https://developers.quaderno.io/api/
  - type: PostmanCollection
    url: collections/quaderno.postman_collection.json
  - type: OpenCollection
    url: collections/quaderno.opencollection.json
  - type: Documentation
    url: https://developers.quaderno.io/guides/checkout/
  - type: Documentation
    url: https://developers.quaderno.io/guides/webhooks/
- aid: quaderno:quaderno-taxes-api
  name: Quaderno Taxes API
  description: Real-time tax rate calculation, jurisdictions, tax codes, and tax ID validation.
  humanURL: https://developers.quaderno.io/api/
  baseURL: https://ACCOUNT_NAME.quadernoapp.com/api
  tags:
  - Taxes
  properties:
  - type: OpenAPI
    url: openapi/quaderno-taxes-api-openapi.yml
  - type: Documentation
    url: https://developers.quaderno.io/api/
  - type: APIReference
    url: https://developers.quaderno.io/api/
  - type: PostmanCollection
    url: collections/quaderno.postman_collection.json
  - type: OpenCollection
    url: collections/quaderno.opencollection.json
  - type: Documentation
    url: https://developers.quaderno.io/guides/checkout/
  - type: Documentation
    url: https://developers.quaderno.io/guides/webhooks/
- aid: quaderno:quaderno-transactions-api
  name: Quaderno Transactions API
  description: Unified sales transactions that both record a sale and calculate tax.
  humanURL: https://developers.quaderno.io/api/
  baseURL: https://ACCOUNT_NAME.quadernoapp.com/api
  tags:
  - Transaction
  tags_raw:
  - Transactions
  properties:
  - type: OpenAPI
    url: openapi/quaderno-transactions-api-openapi.yml
  - type: Documentation
    url: https://developers.quaderno.io/api/
  - type: APIReference
    url: https://developers.quaderno.io/api/
  - type: PostmanCollection
    url: collections/quaderno.postman_collection.json
  - type: OpenCollection
    url: collections/quaderno.opencollection.json
  - type: Documentation
    url: https://developers.quaderno.io/guides/checkout/
  - type: Documentation
    url: https://developers.quaderno.io/guides/webhooks/
- aid: quaderno:quaderno-webhooks-api
  name: Quaderno Webhooks API
  description: Subscriptions that deliver real-time event notifications to your app.
  humanURL: https://developers.quaderno.io/api/
  baseURL: https://ACCOUNT_NAME.quadernoapp.com/api
  tags:
  - Webhook
  tags_raw:
  - Webhooks
  properties:
  - type: OpenAPI
    url: openapi/quaderno-webhooks-api-openapi.yml
  - type: Documentation
    url: https://developers.quaderno.io/api/
  - type: APIReference
    url: https://developers.quaderno.io/api/
  - type: PostmanCollection
    url: collections/quaderno.postman_collection.json
  - type: OpenCollection
    url: collections/quaderno.opencollection.json
  - type: Documentation
    url: https://developers.quaderno.io/guides/checkout/
  - type: Documentation
    url: https://developers.quaderno.io/guides/webhooks/
common:
- type: AgenticAccess
  url: agentic-access/quaderno-agentic-access.yml
- type: DomainSecurity
  url: security/quaderno-domain-security.yml
- type: Authentication
  url: authentication/quaderno-authentication.yml
- type: GitHubOrganization
  url: https://github.com/quaderno
- type: LinkedIn
  url: https://www.linkedin.com/company/quaderno
- type: Website
  url: https://quaderno.io
- type: Documentation
  url: https://developers.quaderno.io
- type: Plans
  url: plans/quaderno-plans-pricing.yml
- type: RateLimits
  url: rate-limits/quaderno-rate-limits.yml
- type: FinOps
  url: finops/quaderno-finops.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

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