Integration · Accounting

Connect Claude & ChatGPT to Quaderno

Ask your AI which Quaderno invoices are still outstanding, what tax applies to a sale, or whether a customer's VAT number is valid. It can create contacts, invoices, estimates, credit notes and expenses, record payments and email invoices to customers. Tax and invoicing questions get answered without opening Quaderno.

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Try asking

“Which invoices are late or still outstanding?”
The AI searches invoices by state and lists the unpaid ones with contact, date and total.
“What tax applies if I sell a digital product to a customer in Germany?”
It calculates the sales tax, VAT or GST for that country and product type and shows the rate and amount.
“Is the VAT number DE123456789 valid?”
It checks the tax ID for the given country and tells you whether it is valid.

What your AI can do

Invoices and estimates

Search, create and update invoices and estimates, convert estimates to invoices, record payments and email invoices.

Tax checks

Calculate the sales tax, VAT or GST for a sale and validate a customer's tax ID.

Contacts, credits and expenses

Manage contacts, issue and send credit notes, record expenses and read receipts, recurring invoices and products.

“Invoice Acme Ltd for 3 hours of consulting at 120 EUR.”
It finds the contact, creates the invoice with one line and lets Quaderno calculate the tax. Nothing is emailed until you ask it to send the invoice.
“Record that invoice 1045 was paid by bank transfer today.”
It records the payment on the invoice with amount, date and payment method. No money is moved.
“Turn estimate 88 into an invoice.”
It converts the accepted estimate into a real invoice and shows you the new invoice.

89 tools for Quaderno

These tools are switched on when you connect. You can switch any of them off, or require your approval before it runs.

approve_proformaVisible to othersAccept a proforma (proforma id). Has effects visible outside this system.
calculate_taxCalculate the sales tax, VAT or GST that applies to a sale, given the customer's `to_country` and optionally postal code, city, tax ID, product type and amount.
cancel_creditDeletesVoid a credit (credit id). Destructive action; may require approval. API summary: Void a credit note.
cancel_invoiceDeletesVoid a invoice (invoice id). Destructive action; may require approval. API summary: Void an invoice.
cancel_receiptDeletesVoid a receipt (receipt id). Destructive action; may require approval.
convert_estimate_to_invoiceVisible to othersTurn an accepted estimate into a real invoice by `proforma_id`. The new invoice is a legal tax document.
create_accountChanges dataCreate a new account. Required: business name, country or email. API summary: Create a custom account.
create_addressChanges dataCreate a new address. API summary: Create an address.
create_contactChanges dataCreate a customer or vendor contact. `first_name` is required (the company name for a company contact); add email, address, country and tax ID as needed. Search first to avoid duplicates.
create_couponChanges dataCreate a new coupon. API summary: Create a coupon.
create_credit_noteChanges dataIssue a credit note (refund document) against an invoice by `invoice_id`, optionally for a partial `credited_amount`. This is a legal tax document and cannot be edited afterwards.
create_credit_paymentChanges dataCreate a new payment for a credit. API summary: Record a payment.
create_estimateChanges dataCreate an estimate (proforma) for a `contact` with line `items`. It is not sent until you email it.
create_evidenceChanges dataCreate a new evidence. Required: document id. API summary: Create an evidence.
create_expenseChanges dataRecord an expense from a vendor `contact` with line `items`, issue date and currency.
create_invoiceChanges dataCreate an invoice for a `contact` with line `items` (description, quantity, unit price). Quaderno calculates the tax. The invoice is not emailed until you send it.
create_paymentChanges dataCreate a new payment. Required: items or payment. API summary: Create a transaction.
create_productChanges dataCreate a new product. Required: code, description, kind, name, product type or tax based on. Search products first to avoid duplicates. API summary: Create a product.
create_receiptChanges dataCreate a new receipt. Required: contact, items or payment method. Search receipts first to avoid duplicates. API summary: Create a receipt.
create_recurringChanges dataCreate a new recurring. Required: contact or items. Search recurrings first to avoid duplicates. API summary: Create a recurring.
create_requestChanges dataCreate a new request. API summary: Requests a report.
create_tax_idChanges dataCreate a new tax id. Required: jurisdiction id or value. API summary: Create a tax ID.
create_webhookDeletesCreate a new webhook. Required: events types or url. Destructive action; may require approval. API summary: Create a webhook.
delete_contactDeletesPermanently delete a contact by contact id. Destructive action; may require approval.
delete_couponDeletesPermanently delete a coupon by coupon id. Destructive action; may require approval.
delete_expenseDeletesPermanently delete a expense by expense id. Destructive action; may require approval. API summary: Delete an expense.
delete_productDeletesPermanently delete a product by product id. Destructive action; may require approval.
delete_recurringDeletesPermanently delete a recurring by recurring id. Destructive action; may require approval.
delete_sessionDeletesPermanently delete a session by session id. Destructive action; may require approval.
delete_tax_idDeletesPermanently delete a tax id by tax id id. Destructive action; may require approval.
delete_webhookDeletesPermanently delete a webhook by webhook id. Destructive action; may require approval.
get_accountGet one account by account id. API summary: Retrieve a custom account.
get_addressGet one address by address id. API summary: Retrieve an address.
get_contactGet one contact by `contact_id`, including name, email, address, tax ID and language.
get_couponGet one coupon by coupon id. API summary: Retrieve a coupon.
get_credit_noteGet one credit note by `credit_id`, with lines, totals and the invoice it refunds.
get_estimateGet one estimate (proforma) by `proforma_id`, with lines, totals and status.
get_evidenceGet one evidence by evidence id. API summary: Retrieve an evidence.
get_expenseGet one expense by `expense_id`, with vendor, lines and totals.
get_invoiceGet one invoice by `invoice_id`, with line items, taxes, totals, payment status and PDF link.
get_jurisdictionGet one jurisdiction by jurisdiction id. API summary: Retrieve a jurisdiction.
get_productGet one product by `product_id`, with code, price, tax class and stock.
get_receiptGet one sales receipt by `receipt_id`, with lines, taxes and totals.
get_recurring_invoiceGet one recurring invoice schedule by `recurring_id`, with frequency, dates and line items.
get_requestGet one request by request id. API summary: Retrieve a reporting request.
get_sessionGet one session by session id. API summary: Retrieve a session.
get_tax_codeGet one tax code by tax code id. API summary: Retrieve a tax code.
get_tax_idGet one tax id by tax id id. API summary: Retrieve a tax ID.
get_webhookGet one webhook by webhook id. API summary: Retrieve a webhook.
list_accountsList accounts. API summary: List all accounts.
list_addressesList addresses.
list_couponsList coupons. API summary: List all coupons.
list_evidenceList evidence. Optional filters: state or document id. API summary: List all evidence objects.
list_jurisdictionsList jurisdictions. Optional filters: country or region. API summary: List all jurisdiction.
list_proforma_deliversList delivers for a proforma. API summary: Deliver a proforma.
list_receipt_deliversList delivers for a receipt. API summary: Deliver an receipt.
list_requestsList requests. API summary: List all reporting requests.
list_tax_codesList tax codes. API summary: List all tax codes.
list_tax_idsList tax ids.
list_webhooksList webhooks. API summary: List all webhooks.
record_invoice_paymentChanges dataRecord a payment received against an invoice by `invoice_id`, with amount, date and payment method. This only records the payment; no money is moved.
reject_proformaVisible to othersDecline a proforma (proforma id). Has effects visible outside this system.
search_contactsSearch customers and vendors by name, email or other text in `q`. Use this to find a contact's ID before creating invoices or other documents.
search_credit_notesSearch credit notes by text in `q`, `state` or `date` range.
search_estimatesSearch estimates (proformas) by text in `q`, `contact`, `state` or `date` range.
search_expensesSearch expenses (purchase invoices) by text in `q`, `contact`, `state` or `date` range.
search_invoicesSearch invoices by text in `q`, `contact`, `state` (e.g. outstanding, paid, late) or `date` range. Use to find unpaid or recent invoices.
search_productsSearch your product and service catalog by text in `q`.
search_receiptsSearch sales receipts by text in `q`, `contact` or `date` range.
search_recurring_invoicesSearch recurring invoice schedules by text in `q`, `contact`, `state` or `date`.
send_credit_noteEmail a credit note to its customer by `credit_id`. This sends a real email to the customer.
send_invoiceEmail an invoice to its customer by `invoice_id`. This sends a real email to the customer.
submit_invoiceVisible to othersMark uncollectible a invoice (invoice id). Has effects visible outside this system. API summary: Mark an invoice as uncollectible.
update_accountChanges dataUpdate an existing account identified by account id. API summary: Update a custom account.
update_addressChanges dataUpdate an existing address identified by address id. API summary: Update an address.
update_contactChanges dataUpdate a contact's details by `contact_id` (first_name must be passed again), such as email, address, country or tax ID.
update_couponChanges dataUpdate an existing coupon identified by coupon id. API summary: Update a coupon.
update_creditChanges dataUpdate an existing credit identified by credit id. API summary: Update a credit note.
update_evidenceChanges dataUpdate an existing evidence identified by evidence id. API summary: Update an evidence.
update_expenseChanges dataUpdate an existing expense identified by expense id. API summary: Update an expense.
update_invoiceChanges dataUpdate an invoice's notes, tags, attachment, payment details or custom metadata by `invoice_id`. Amounts and lines cannot be changed here.
update_productChanges dataUpdate an existing product identified by product id. API summary: Update a product.
update_proformaChanges dataUpdate an existing proforma identified by proforma id. API summary: Update a proforma.
update_proforma_revertsVisible to othersUpdate an existing revert identified by proforma id. Has effects visible outside this system. API summary: Revert a proforma.
update_recurringChanges dataUpdate an existing recurring identified by recurring id. API summary: Update a recurring.
update_sessionChanges dataUpdate an existing session identified by session id. API summary: Update a session.
update_tax_idChanges dataUpdate an existing tax id identified by tax id id. API summary: Update a tax ID.
update_webhookDeletesUpdate an existing webhook identified by webhook id. Destructive action; may require approval. API summary: Update a webhook.
validate_tax_idCheck whether a customer's VAT or tax number is valid, given `country` and `tax_id`.

Set up in three steps

1
Pick the app
Create a free HeyMyApps account and choose Quaderno from the app list.
2
Paste your key
Enter three things: your Quaderno account name (the "acme" in acme.quadernoapp.com), your private API key from quadernoapp.com/users/api-keys, and leave the password field empty.
3
Add the link to your AI
You get a personal MCP link. Add it to Claude, ChatGPT or Cursor:
1. Click your name, then Settings › Connectors › Add custom connector.
2. Paste your link as the Remote MCP server URL.
3. Switch it on from the + menu in a chat.

Questions

What can the AI do in Quaderno?

The AI can search and read contacts, invoices, credit notes, receipts, estimates, expenses, recurring invoices and products. It can create and update contacts and invoices, create estimates, credit notes and expenses, record invoice payments, convert estimates to invoices, email invoices and credit notes, calculate tax and validate tax IDs.

Does the AI see my Quaderno API key?

No. Your Quaderno credentials are encrypted at rest and never shown to the AI. After you save them, they are not shown again, not even to you. The AI only sees the results of the tools it calls.

Can I control what the AI is allowed to do?

Yes. You choose which tools are switched on, so you can start with lookups and tax checks only. Tools that email customers, like send_invoice, can stay off until you want them, and converting an estimate into an invoice can require your approval before it runs. Every tool call is logged.

Does it work with ChatGPT?

Yes. In ChatGPT go to Settings › Apps & Connectors › Advanced and turn on Developer mode, then add your HeyMyApps link. Developer mode needs a paid ChatGPT plan: Plus, Pro, Business or Enterprise. The same link also works in Claude (Settings › Connectors › Add custom connector), Cursor and other MCP clients.

What does it cost?

HeyMyApps has a free plan with no credit card required. Paid plans bill per completed task. You also need your own Quaderno account.

Why is the password field left empty?

Quaderno uses your private API key as the username and no password. So you paste the API key, leave the password empty and add your account name, which tells HeyMyApps which Quaderno account to call.