sevdesk in ChatGPT and Claude: open invoices, unpaid bills and the bank

How to connect sevdesk to ChatGPT or Claude

A client swears they paid in October. sevdesk still shows their invoice as open, and there’s a payment in the bank from a name you don’t recognise. With sevdesk connected, ChatGPT or Claude can check both while you’re still on the phone.

1. Get APIUniCon into ChatGPT or Claude with the setup guide, unless it’s already there from another service.
2. Ask for the connection in the chat: “Connect my sevdesk”. If the AI wants to read up first, give it the sevdesk API documentation.
3. Copy your API token. In sevdesk it sits in the settings under Users, on your administrator user. The documentation is clear that only administrators have one: “every sevdesk administrator has one API token”.
4. Paste the token on our page, the link the AI sends you. sevdesk expects it as it is, in the Authorization header of every request, and that’s how we send it. We store it encrypted; only the answers to your questions reach the chat.
5. Wait a few seconds for the test request. The AI will say what it can read: invoices, supplier bills and receipts, contacts and bank accounts.

We checked on 13 November 2026: neither the ChatGPT plugin directory nor Claude’s connector directory listed sevdesk.

What to ask about invoices, bills and the bank

Good questions to start with:

• Which invoices are overdue, by how many days, and who owes the most?
• How much will come in over the next 14 days if everyone pays on time?
• Which supplier bills are due this week, and how much in total?
• Which payments in the bank aren’t booked to an invoice or a bill yet?
• Is there a payment in the bank that matches invoice RE-1042?
• Which invoices are still drafts and were never sent?
• Which clients paid late more than once this year?
• How much VAT is on the invoices we wrote in October?

Cases from a small studio in Leipzig

The web studio in these examples is fictional, and so are its clients and figures. Ask the same questions and you’ll get your own.

Who owes what

“Which invoices are overdue, and who owes the most?” sevdesk marks an invoice that has been sent but not paid as open, and it counts as due once its payment date has passed. The AI lists those and sorts them.

7 invoices are overdue, €14,280 in total. Weber Logistik owes the most: €5,950 on RE-1031, 41 days late. Café Brühl has two, €1,190 on RE-1042 and €830 on RE-1056, 19 and 6 days late. The other 4 add up to €6,310. RE-1049 for €2,380 is partly paid, €1,000 is still open.

That last line matters. Since June 2024 sevdesk keeps partly paid invoices in a status of their own, so the AI can tell “nothing came” from “some of it came”.

“We paid last week”

Café Brühl says they paid. The question: “Is there a payment in the bank that matches Café Brühl’s invoices?” sevdesk keeps the transactions of each bank account you connected, and the AI looks for ones not yet booked to anything.

Yes. On 4 November €1,190 came in from BRUEHL GASTRO GMBH and isn’t booked yet. It matches RE-1042 exactly. RE-1056 for €830 is still unpaid. Two more unbooked payments, €240 and €96, don’t match any open invoice, so you’ll want to look at those yourself.

What has to go out this week

The other side of the books: “Which supplier bills are due by Friday?” Bills and receipts you entered in sevdesk carry their own status, from draft to unpaid, due and paid.

4 bills are due by Friday, €3,140 in total: hosting €89, the freelancer invoice from M. Schulz €2,400, the office rent share €560 and a software licence €91. The bank account had €9,870 on 12 November, so all four are covered with the incoming €1,190 from Café Brühl on top.

What the AI can do in sevdesk

Some of the follow-up the AI can do itself. Every email, reminder or booking is shown to you first, and nothing happens until you confirm.

• “Send Weber Logistik a reminder for RE-1031.” sevdesk can create a reminder invoice from an overdue one; you see the amount, any fee and the text before it’s created or emailed.
• “Book the €1,190 from Café Brühl to RE-1042.” You see the bank line and the invoice side by side, and the invoice turns paid after you agree.
• “Email invoice RE-1058 to the client.” You see the address, the subject and the attached PDF first.
• “Put RE-1057 back to draft, the amount is wrong.” sevdesk allows an invoice to go back to draft; the AI tells you which status it’s in now and what changes.
• “Mark the hosting bill as paid, it went out this morning.” This only records the payment in sevdesk, against the bill, once you confirm.

If something goes wrong

If sevdesk answers that the token is wrong, it was most likely regenerated in sevdesk or belongs to a user who was removed. Copy the current token and tell the AI “Update the sevdesk key”; it sends you a fresh link to our page. If a long list comes back cut short, ask for it by month: sevdesk returns at most 1,000 records per request, and the AI pages through them, but a whole year of transactions on a busy account takes a moment.