Duplicate supplier invoices are one of the most common ways money leaks out of accounts payable. Bookkeepers and AP teams can check a payment run before it goes to the bank.
Claude can spot obvious repeats in a short list, but it saves no evidence. The Duplicate Invoice Check server scans a whole batch, groups candidate duplicates with a reason for each, and exports a CSV for the approver. It runs locally. It doesn't approve or block payments.
What you get
Check the payment run
AP clerk at a logistics firm in Lodz
| Tool call | What it did |
|---|---|
| duplicate_invoice_check | Groups candidate duplicates with reason codes |
| report_page | Pages through each group's members |
3 candidate groups, for example FV/2026/104 and FV-2026-104 from the same supplier flagged as normalized_reference.
Free to start. Duplicate Invoice Check Pro is $19 once. Free vs Pro
Claude can scan a short pasted list and spot obvious repeats. On a few hundred rows it can miss near-repeats, it can't save the result as evidence, and it gives no CSV you can attach to the approval.
Duplicate Invoice Check takes a batch of invoice records, returns candidate duplicate groups with the reason for each, saves the report and exports it as CSV. It runs locally from a source checkout. It doesn't read PDFs or approve payment.
Example scenarios built on the real tools of Duplicate Invoice Check. Names and amounts are invented.
Check these 85 invoices from the Hartley Builders AP export for duplicates before Thursday's payment run, and give me the CSV.
A list of candidate duplicate groups with reasons, and a CSV to attach to the payment approval.
Here are the 240 supplier invoices in Friday's payment run. Any duplicates?
3 candidate groups, for example FV/2026/104 and FV-2026-104 from the same supplier flagged as normalized_reference.
About 60 min saved (estimate)
Export the duplicate report as CSV so I can attach it to the approval email.
A CSV with the original fields, the candidate flag and why each one was grouped.
About 15 min saved (estimate)
Every example here works on the free tier. One $39 key removes the limits on all of them. Pricing
Duplicate Invoice Check runs on your machine. One line with Node.js, or the .mcpb file for Claude Desktop.
Run it locally (Node.js 18+)
npx -y @theluckystrike/mcp-duplicate-invoice-check
| Free ($0, no key) | Pro ($19 once) |
|---|---|
| Full duplicate check, all reasons | Unlimited saved reports |
| Paging and CSV export | |
| 3 saved reports |
servers/duplicate-invoice-check/src/store.ts:9 (FREE_REPORT_CAP = 3), :63; servers/duplicate-invoice-check/README.md:16
Match supplier invoice lines to purchase orders and receipts by SKU with tolerances. Explainable exceptions. Uses the Three Way Match server. 6 tools.
You get: Exception report Supplier Statement CheckCompare a supplier statement with your AP open items by exact reference. Get the differences in one list. Uses the Supplier Statement Check server. 6 tools.
You get: Mismatch report Asset RegisterFixed asset register with bundled MACRS, HMRC and Polish KST tables. Schedules and journals from one prompt. Uses the Asset Register server. 7 tools.
You get: ReportDuplicate Invoice Check Pro: $19 once