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.
Limited machine-readable signal and partial portal coverage — documentation a human can read, but little a machine or agent can consume without scraping.
API Evangelist profiles Quaderno the way a machine reads it — 21 machine-readable artifacts across 14 APIs, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.
Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — Quaderno scores 40.3/100 (thin), with a separate agent-readiness read of 48/100 (agent ready). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.
Kin Score
This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance.
Kin Score
How this is scored →scored 2026-07-27 · rubric v0.5
How we profile Quaderno
Each block below is one kind of artifact we hold for Quaderno. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.
APIs 14
Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.
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 within the panel for all 14 ·
Open Collections 1
Open, tool-agnostic collections carry the same runnable value as Postman without locking you to one client — the portable, forkable form of the same exercise.
Open, tool-agnostic API collections (OpenAPI-derived and Bruno).
Quaderno API
OPEN COLLECTIONPricing Plans 1
Pricing is part of the interface. Machine-readable plans tell you what a tier costs and includes before you commit — one of the six things the Kin Score reads for commercial clarity.
Published pricing tiers and plan structures.
Rate Limits 1
Rate limits are the difference between a demo that works and a production integration that doesn't fall over. Publishing them is an operational-transparency signal — and a hard requirement for any agent that plans its own throughput.
Documented rate limits and quota policies.
Quaderno Rate Limits
RATE LIMITSFinOps 1
Cost, billing, and metering signals let a buyer model the financial operations of an API before it's live. We profile them for the same reason we profile pricing: the money is part of the contract.
Cost, billing, and metering signals for API financial operations.
Quaderno Finops
FINOPSSecurity Posture 2
Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Agentic Access 1
An x-agentic-access contract marks which operations are safe for an agent to run on its own and which need a human in the loop. It is the difference between an API an agent can use and one it can use safely.
Recommended x-agentic-access execution contracts for AI agents.
Resources
Every other property we hold for Quaderno — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.
Documentation 1
Reference material describing how the API behaves
Agent Surfaces 1
MCP servers, agent skills, and machine-readable catalogs
Build 1
SDKs, sample code, and the tooling you integrate with
Access & Security 2
Authentication, authorization, and security posture
Operate 1
Status, limits, changes, and where to get help
Commercial 2
Pricing, plans, and the legal terms of use
Company 2
The organization behind the API
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