n8n Workflow: Paid Order Invoices & Pick Lists via Gmail

Automatically send paid order invoices via Gmail—and push pick lists to Slack

This n8n workflow triggers when an order is paid, generates a PDF invoice and an Excel pick list using Cloud Office Print, emails the invoice through Gmail, archives it in Google Drive, and notifies Slack with low-stock warnings.

What this workflow does

• Receives payment events: Listens for a POST webhook containing an order_id secured with header authentication.
• Pulls order + customer data: Fetches the order from your shop API, then retrieves each product’s SKU/stock/weight and loads the related customer record.
• Builds invoice and fulfillment data: Computes totals and tax from the combined order information and flags low-stock items for visibility in the pick list.
• Generates a PDF invoice from templates: Downloads a Word invoice template from Google Drive and uses Cloud Office Print to produce a PDF invoice.
• Sends invoice by email: Emails the generated PDF invoice to the customer via Gmail.
• Slack alerting + pick list delivery: If sending fails, Slack is alerted. Otherwise, Slack receives the filled pick list, including low-stock warnings.
• Archives the invoice: Uploads the PDF invoice to a specified Google Drive archive folder.
• Finalizes fulfillment: Downloads an Excel pick-list template from Google Drive, fills it via Cloud Office Print, posts it to Slack, and updates the shop API marking the order as invoiced.

Use cases

• For e-commerce teams that need instant invoice delivery after payment.
• Warehouses that want Slack-based pick list updates and low-stock warnings without manual spreadsheet work.
• SaaS operators standardizing invoice/pick-list generation with Google Drive templates and automated record updates in the shop API.

Technical details

• n8n nodes/integrations: webhook, set, code, split out, gmail, slack
• Includes Cloud Office Print node setup via n8n-nodes-cloudofficeprint and an API key credential.
• Uses Google Drive OAuth to fetch DOCX/XLSX templates and to archive generated invoices.