Approve Invoices with Claude Vision + Google Drive & Sheets (n8n)

Automatically extract, validate, and approve invoices using Claude Vision + Google Drive & Sheets (n8n)

Stop manual invoice triage. This n8n workflow watches your Google Drive Inbox for new invoice files, uses Anthropic Claude Vision to extract structured fields, verifies totals and duplicates in Google Sheets, and then either auto-approves low-risk invoices or pauses for human approval—finally logging results and moving files to the right folder.

What this workflow does

• Monitors an “Inbox” folder in Google Drive (or can be run manually with a test file ID).
• Downloads the invoice file, converts it to base64, and prepares a request for Claude (Anthropic Messages API) with vision to extract invoice data as JSON.
• Parses the Claude response and flags the run if the extraction cannot be parsed.
• Validates invoice math by checking that subtotal + tax matches the extracted total.
• Detects duplicates by reading a Google Sheets ledger to compare invoice numbers.
• Routes invoices for decision: If extraction fails, totals mismatch, or a duplicate is found—or if the invoice is at/above your configured threshold—the workflow sends approve/reject links to a webhook and waits for the human decision.
• Logs and archives: Calculates the vendor’s prior approved spend from Google Sheets, appends a normalized ledger row with the final approval status, then moves the file to Processed or Flagged and sends an outcome notification via webhook.

Use cases

• Accounts payable teams who need consistent invoice intake from scanned PDFs/images.
• SaaS operators automating invoice approval workflows with clear audit logging in Google Sheets.
• n8n users looking for an end-to-end invoice processing automation with AI extraction plus deterministic validation.

Technical details

• Integrations: Google Drive, Google Sheets, Anthropic Messages API (Claude Vision).
• n8n workflow logic & nodes: if, set, code, wait, “sticky note”, Google Drive (trigger/download/move).
• Run routing: webhook-based approve/reject step using a wait for the decision.

Setup

Connect your Google Drive credentials with access to the Inbox, Processed, and Flagged folders, then configure the workflow to point to your Sheets ledger and approval threshold.