n8n Inventory Forecasting & PO Routing with Google Sheets + OpenAI

Automated inventory forecasting and PO routing in n8n—powered by Google Sheets + OpenAI

This n8n workflow forecasts SKU demand from your Google Sheets, drafts purchase-order justifications with OpenAI, and routes Critical and Warning items for Telegram review—while sending Slack alerts and a daily procurement email digest.

What this workflow does

Run daily on a schedule, the workflow reads these tabs from your Google Sheets:

• Sales History, Inventory, Vendors, and Purchase Orders

It then:

• Calculates 7/30-day demand and estimates days of stock remaining for each SKU.
• Skips SKUs that have recent open POs to avoid duplicate purchasing.
• Classifies each SKU as Critical, Warning, Watch, or OK.
• For Critical and Warning SKUs, calls OpenAI (gpt-4o-mini) to generate a short PO justification, then appends a new row to the Purchase Orders sheet with draft details and recommended quantities.
• Sends Critical items to Telegram with inline Approve/Reject buttons and posts a critical stockout alert to Slack.
• Sends Warning items to Telegram as a draft notification.
• Logs Watch items back to Google Sheets without sending messages.
• Builds an HTML summary (Critical/Warning/Watch) and emails the daily digest to procurement via Gmail.
• After Telegram approval callbacks, updates PO status in Google Sheets; on approval emails, sends PO details to the supplier via Gmail and confirms the outcome in Telegram.

Use cases

• Prevent stockouts by automatically routing at-risk SKUs to decision-makers.
• Speed up procurement by drafting PO justifications using OpenAI and logging everything in Google Sheets.
• Provide a daily operational digest to suppliers and internal teams via Gmail and Slack.

Technical details

• Integrations: Google Sheets (OAuth2), OpenAI (gpt-4o-mini), Telegram, Slack, Gmail.
• Workflow nodes used: if, code, gmail, merge, slack, switch.
• Setup requirement: add Google Sheets OAuth2 credentials and replace YOUR_GOOGLE_SHEET_ID (including the spreadsheet tab references used by the workflow).