MCP server for Quaderno — tax-rate calculation, invoices, contacts, products, receipts & expenses. Hosted by usefulapi: connect it to Claude, ChatGPT, Cursor or any MCP client.
Turn on the Quaderno connector, then ask in plain words. The AI picks the tools.
For online sellers and accountants who handle tax and invoices with Quaderno.
The AI calculates the VAT, GST or US sales tax rate for a product and the customer's location. Nothing is created in your account.
The AI lists your newest invoices with filters and opens one for items, taxes and payments. It also lists credit notes and receipts.
The AI lists the expenses (bills you received) and the tax jurisdictions where your account is registered to collect tax.
The AI finds contacts and reads one, or creates a new customer or vendor with a name and details. It can also update an existing contact.
Changes dataThe AI creates an invoice for a contact with items, or records a sale or refund transaction so Quaderno computes the tax. It can add a product first.
Changes dataThe login page asks for your Quaderno API key and Account subdomain.
Find your API key in Quaderno → your account → API keys. Your key is used only to call the API on your behalf and to derive a private account id; it is never shown to anyone.
Team and Enterprise: an Owner adds the connector for the organization first.
No Add custom MCP server option? It depends on your account or workspace settings: see OpenAI's guide.
Run this command, then run /mcp in Claude Code to log in:
Add to Cursor or add this to ~/.cursor/mcp.json:
{
"mcpServers": {
"quaderno": {
"url": "https://quaderno.usefulapi.io/mcp"
}
}
} Add to VS Code or add this to .vscode/mcp.json:
{
"servers": {
"quaderno": {
"type": "http",
"url": "https://quaderno.usefulapi.io/mcp"
}
}
} Run these commands. The second one opens the login page:
Windsurf, Cline, Zed and other MCP clients: add this URL as a remote MCP server (Streamable HTTP). The client then opens the login page in your browser.
Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your Quaderno API key and Account subdomain. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.
| Plan | Price | Limit |
|---|---|---|
| Free | $0 | 50 tool calls / month |
| Pro | $9/mo · $90/yr | 10,000 tool calls / month |
| Pro+ | $39/mo · $390/yr | 100,000 tool calls / month |
Each paid plan covers this Quaderno server only. Ask your AI to run quaderno_upgrade and choose Pro or Pro+, billed monthly or yearly (it returns a Stripe Checkout link). If you already have Pro, ask to change it to Pro+. The change requires your confirmation, keeps your billing interval and charges the price difference for the rest of the period immediately. Cancel any time with quaderno_cancel_subscription: your paid plan continues to the end of the paid period, with no refund for the current period, and asking to resume the same plan with quaderno_upgrade before then undoes the cancel. Or write to [email protected].
quaderno_pingquaderno_calculate_taxquaderno_list_invoicesquaderno_get_invoicequaderno_list_contactsquaderno_get_contactquaderno_list_itemsquaderno_get_itemquaderno_list_credit_notesquaderno_get_credit_notequaderno_list_receiptsquaderno_get_receiptquaderno_list_expensesquaderno_get_expensequaderno_list_tax_codesquaderno_list_jurisdictionsquaderno_list_webhooksquaderno_requestquaderno_create_contactquaderno_update_contactquaderno_create_itemquaderno_create_invoicequaderno_create_transactionquaderno_usage_statusquaderno_request_featurequaderno_upgradequaderno_cancel_subscriptionFind the tax rate for a sale. Review invoices, credit notes and receipts. List expenses and the jurisdictions you collect in. Look up, add or update a customer or vendor. Create products or invoices, or record sales and refunds. See what you can do for the details.
No. usefulapi is an independent service. It is not affiliated with or endorsed by Quaderno. The server calls the Quaderno API with your own Quaderno access, so it sees only the data that your account can see.
Yes. In Claude, add this server's URL as a custom connector. In ChatGPT, add it as a custom MCP server in Plugins. Then log in once. Cursor, VS Code, Claude Code and Codex work too. See the setup steps.
The login page asks for your Quaderno API key and Account subdomain. See Before you connect for where to find them.
No. Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your Quaderno API key and Account subdomain. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.
The login stores them encrypted in the authorization grant of your connection. The server uses them to call the Quaderno API for you and to derive a private account id for usage metering. usefulapi does not show them on any page or in any reply. To stop all access, remove the connector and change or delete these credentials in Quaderno.
Yes, if you approve it. 5 of the 23 Quaderno tools can create or change data. The other 18 are marked read-only. Most MCP clients ask you to approve a tool call before it runs.
The Free plan gives 50 tool calls / month. Pro costs $9/mo or $90/yr, with 10,000 tool calls / month. Pro+ costs $39/mo or $390/yr, with 100,000 tool calls / month. Each subscription covers this Quaderno server only. Cancel any time: your paid plan then runs to the end of the paid period. Run quaderno_usage_status to see how many calls you used.
Ask the AI to run quaderno_upgrade and choose Pro or Pro+, billed monthly or yearly: it returns a Stripe Checkout link. If you already have Pro, ask to change it to Pro+. After you confirm, your existing subscription changes in place, keeps its billing interval and charges the price difference for the rest of the period immediately. To cancel, run quaderno_cancel_subscription. Your paid plan continues to the end of the paid period.
Tell the AI what you wanted to do. It can send the request with quaderno_request_feature. We store the text with the server name, the type of AI client and the tool you tried, not with your account, and read every request when we plan new tools. You can send up to 5 requests per day.
Any client that supports remote MCP servers (Streamable HTTP) with OAuth login: Claude (web and desktop), Claude Code, ChatGPT, Codex, Cursor, VS Code, Windsurf and others.
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.
Need a tool this server does not have, or a connection to another system? We build custom integrations and MCP servers.