AI Workflow Automation in Node.js: Invoice to PO Matching with Claude

Description and use

Automating invoice-to-PO matching with Claude in Node.js automatically approves matching invoices and queues mismatches for review.

Problem

Finance teams need to verify invoices against purchase orders efficiently while ensuring accuracy and auditability.

Outcome

The pipeline reduces manual effort by approving clean invoices automatically while still catching mismatches for audit.

Workflow

• 1. Send PDF to Claude with a tool call that returns structured JSON.
• 2. Claude extracts fields (invoice_number, po_number, supplier_name, currency, printed_total, lines, unreadable_fields) exactly as printed.
• 3. Node.js code compares extracted data to the corresponding PO in the ERP.
• 4. If all line items and totals match, the invoice is approved automatically.
• 5. If any mismatch or unreadable field is detected, the invoice is placed in an exception queue for manual review.

Evidence

Send the PDF to Claude and force a tool call. The answer comes back as JSON that follows your schema, not free text.

Source

Approval is a rule, and a rule should give the same answer every time. A language model is very good at reading a messy layout and working out that "Units" means quantity. It is the wrong place to decide whether a small price difference is acceptable.

Source