Paste an invoice and have it checked
Open your invoice, select everything and paste it below. The tool extracts the fields, does the IBAN check digit calculation, validates the VAT number, re-adds the amounts and tells you what doesn't add up. Everything happens in this tab — there is no server receiving your invoice.
No invoice to hand? Try , or .
What exactly gets checked
The IBAN. Every bank account number has a check digit (mod-97). If it doesn't match, it has been mistyped or tampered with. A changed bank account number on an otherwise correct invoice is the most common form of invoice fraud.
The VAT number. Dutch numbers have an eleven-proof check. If it fails for a legal entity, a digit is wrong. For sole traders it often fails legitimately — their VAT ID has been randomly assigned since 2020 — so we flag that as a signal, not as an error.
The amounts. Does subtotal plus VAT add up to the total? And does the VAT amount match a single rate? If no percentage is shown, we infer it: if 19.5% comes out, there are lines at different rates that haven't been split. That is exactly what you break down for your tax return.
The dates. If it says 03-08-26, that could be 3 August or 8 March. Without a month name it cannot be resolved, and a person should look at it rather than a system guessing.
Why this runs in your browser
An invoice contains your suppliers, your amounts and your bank account number. That shouldn't go to a website you happen to land on. This page has no server side: you can disconnect from the internet and it keeps working.
And in practice?
This is the calculation side. A real implementation also involves reading PDFs and scans, recognising your specific suppliers, and integrating with your accounting package so that a booking actually gets posted. We build that to measure.
Talk about invoice processing