Duplicate invoice checker
Drop in an export of your bills and see which ones look like they were entered twice: the same invoice with a different prefix, a number with one digit swapped, or one supplier set up under two names. The whole check runs in your browser, so your data stays on your machine.
Your file is read by your browser and never uploaded. Close the tab and it's gone. The amounts shown are in whatever currency the file uses.
Duplicates rarely look identical
INV-0042 is the same as 42
Before comparing, the checker ignores the parts people retype differently: prefixes like INV or Bill No, dashes, spaces and leading zeros. Supplier names lose Ltd, LLC and similar endings, so Acme Trading Ltd and ACME Trading match.
One wrong digit still counts
When the supplier and amount match and the invoice numbers are one character apart, like 58817 and 58871, that's almost always the same bill keyed in twice with a typo.
Strong matches first
Exact repeats, look-alike numbers and suppliers set up twice are flagged as likely problems. Same amount within a few weeks is shown separately as a softer check, since recurring bills look the same on purpose.
What this can't do: see invoices that never made it into the export, or tell you which copy of a duplicate is the right one. It works on the numbers in the file, not the documents behind them. For the full picture of how duplicates slip through, read how duplicate payments happen and how to stop them.
Before you run it
How do I export my bills as a CSV?
Most accounting systems have a bills, payables or purchases report with an export button. Pick a date range, export to CSV, and drop the file here. If you only have an Excel file, open it and save it as CSV first.
Is my data uploaded anywhere?
No. The file is read by your browser and checked right there. Nothing is sent to Clearline or anyone else, and nothing is kept once you close the tab.
Why does it flag invoices that aren't duplicates?
Some bills repeat on purpose. Rent, subscriptions and retainers come in at the same amount every month, so they can show up under the same-amount check. That check is there for a second look, not as proof of a problem.
Can it catch duplicates that were already paid?
It can find them, as long as the paid bills are in the export. Include both paid and unpaid bills for the period and anything paid twice will show up. Recovering the money is a conversation with the supplier.