usefulapi

Quaderno MCP server. MCP server for Quaderno — tax-rate calculation, invoices, contacts, products, receipts & expenses.

Claude

Open Settings → Connectors → Add custom connector
Paste this URL:
https://quaderno.usefulapi.io/mcp
Authenticate with Quaderno when prompted

Cursor · VS Code · Windsurf · Cline

Add to your MCP config, then reload & authorize:

{
  "mcpServers": {
    "quaderno": {
      "url": "https://quaderno.usefulapi.io/mcp"
    }
  }
}

live25 toolsFree 100 tool calls / monthPro $9/mo · $90/yr

Tools 25

Tool	Type	What it does
`ping`	read	Ping Ping Quaderno to verify the API key and account subdomain resolve and authenticate — a quick way to confirm the connection works before doing real work.
`calculate_tax`	read	Calculate tax Calculate the correct tax rate and amount for a sale from the customer's location and product, applying Quaderno's per-jurisdiction VAT / GST / US sales-tax rules; read-only and creates no record.
`list_invoices`	read	List invoices List invoices newest-first with filters for search text, date range, state (outstanding/late/uncollectible/paid) and contact, cursor-paginated for large accounts.
`get_invoice`	read	Get invoice Fetch a single invoice by id in full detail, including line items, taxes, payments, permalink and PDF link.
`list_contacts`	read	List contacts List contacts (customers and vendors) newest-first, searchable by name, email or tax ID, with cursor pagination.
`get_contact`	read	Get contact Fetch a single contact by id, including its kind, names, email, country, tax ID and tax status.
`list_items`	read	List items List products/items in the catalog newest-first, each with code, name, kind, unit cost, tax class, currency and stock, cursor-paginated.
`get_item`	read	Get item Fetch a single product/item by id with its full pricing and tax configuration.
`list_credit_notes`	read	List credit notes List credit notes (refund documents) newest-first, filterable by search text, date range and contact, with cursor pagination.
`get_credit_note`	read	Get credit note Fetch a single credit note by id in full detail.
`list_receipts`	read	List receipts List receipts newest-first, filterable by search text, date range and contact, with cursor pagination.
`get_receipt`	read	Get receipt Fetch a single receipt by id in full detail.
`list_expenses`	read	List expenses List expenses (bills you received) newest-first, filterable by search text, date range and vendor, with cursor pagination.
`get_expense`	read	Get expense Fetch a single expense by id in full detail.
`list_tax_codes`	read	List tax codes List the product tax codes Quaderno supports (id, name, description), used as the tax_code on products and tax calculations.
`list_jurisdictions`	read	List jurisdictions List the tax jurisdictions where the account is registered to collect tax, each with its name, country and region.
`list_webhooks`	read	List webhooks List the account's configured webhooks with their id, target URL and subscribed events.
`quaderno_request`	read	Request Power-user escape hatch to GET any read-only Quaderno API path not wrapped by a dedicated tool, for endpoints like tax IDs or evidence.
`create_contact`	write	Create contact Create a contact (customer or vendor) with a kind and name, plus any other Quaderno contact attribute via a free-form fields passthrough.
`update_contact`	write	Update contact Update an existing contact by id, changing only the fields you pass (name, email, country, tax ID, or any raw field).
`create_item`	write	Create item Create a product/item in the catalog with a name and unit cost, plus optional code, kind, product type, currency and any raw field.
`create_invoice`	write	Create invoice Create an invoice for a contact with line items, currency, issue/due dates and notes, returning the created invoice with its permalink and PDF.
`create_transaction`	write	Create transaction Record a sale or refund transaction for which Quaderno computes the tax and produces the compliant invoice or credit-note document.
`quaderno_usage_status`	meta	Usage status (free-tier meter) Report the caller's current free-tier usage this month: calls used, monthly limit, remaining, and whether the cap is reached. Read-only; does not count against the meter.
`quaderno_upgrade`	meta	Upgrade to Pro (unlimited) Subscribe to the Pro plan for UNLIMITED Quaderno tool calls (the free tier caps monthly usage). Choose monthly ($9/month) or yearly ($90/year — 2 months free) billing. Returns a Stripe Checkout link to open in your browser; after payment your account upgrades automatically. Read-only; does not count against the meter.

Pricing

Plan	Price	Limit
Free	$0	100 tool calls / month
Pro	$9/mo · $90/yr	Unlimited

This is a Model Context Protocol endpoint — meant to be connected from an AI client, not opened in a browser. An invalid_token response at the URL is the auth gate working as designed; clients authenticate automatically.