Claude Invoice PDF Extractor to Google Sheets (n8n)

Automatically extract invoice data from PDF files into Google Sheets using Claude (n8n)

This n8n workflow watches a Google Drive folder for new invoice PDFs, uses Anthropic Claude to extract structured invoice fields, and then saves the results into Google Sheets—including duplicate detection and logging.

What this workflow does

• Monitors Google Drive: Triggers whenever a new file is created in a specified Google Drive folder.
• Downloads and prepares the PDF: Retrieves the PDF from Google Drive and converts it to base64 for processing.
• Uses Claude to extract JSON: Sends the base64 PDF to the Anthropic Messages API (Claude) with instructions to extract invoice data as structured JSON.
• Parses and enriches results: Interprets Claude’s JSON response and records metadata such as:
  • file name
  • source Google Drive file ID
  • processing timestamp
• Detects duplicates: Searches the Google Sheets “Invoices” tab for an existing row with the same invoice number.
• Logs duplicate warnings: If a match exists, appends a warning entry to the “Duplicates” tab.
• Appends new invoice rows: If no match is found, adds a new row to “Invoices”, including totals and line items JSON.

Use cases

• Accounts teams: centralize invoice processing by turning incoming invoice PDFs into a searchable Google Sheets ledger.
• SaaS operators: keep financial records up to date automatically as invoice files land in Google Drive.
• Automation engineers: reduce manual data entry by combining n8n + Claude + Google Sheets with duplicate handling.

Technical details

• n8n nodes / components: google drive, http request, google sheets, code, if, and supporting workflow logic (including notes/sticky notes).
• Claude integration: Calls the Anthropic Messages API to extract invoice fields as JSON.
• Google Sheets tabs: Requires tabs named “Invoices” and “Duplicates” with headers matching the fields written by the workflow (e.g., Invoice Number, Vendor, Invoice Date, Subtotal, Tax, Total, Currency, and line items).