WhatsApp Bill Splitter n8n Workflow: WAHA + Gemini + Sheets

Split WhatsApp bills automatically—receipt OCR, calculated shares, and playful reminders in one n8n workflow

This WhatsApp Bill Splitter n8n Workflow uses WAHA to run a WhatsApp bill-splitting bot, Google Gemini to extract receipt totals via OCR, OpenRouter to generate humorous bill and reminder messages, and Google Sheets to track sessions, contacts, bills, and payment status—plus daily reminders at 7 PM.

What this workflow does

• Receives group instructions via WhatsApp using a WAHA webhook, and ignores messages from numbers not on a `whitelist`.
• Processes receipt images: when a message includes receipt media, the workflow downloads the image via WAHA and uses Google Gemini to extract items/tax/total.
• Collects item assignments: it asks the group to reply in the format “Name: item1, item2”, then stores the OCR session result in a Google Sheets Session tab.
• Calculates proportional shares when a follow-up assignment arrives: it loads the latest OCR session and contacts from Google Sheets, matches item keywords to receipt items, and computes each person’s portion including proportional tax.
• Sends personalized bills: for each participant, it uses OpenRouter to generate a short humorous bill message and sends it via WAHA, logging unpaid entries in the Google Sheets Bills tab.
• Marks payments as done when a message contains payment confirmation (e.g., “paid”/“done”), updating the newest matching unpaid bill by WhatsApp number (or name fallback).
• Automates daily reminders at 7 PM: pulls unpaid bills from Google Sheets, applies a same-day anti-spam guard, generates the reminder tone (gentle/firm/savage) with OpenRouter, sends via WAHA, and updates the reminder tracking field (lastR...).

Use cases

• Friends splitting restaurant bills in a WhatsApp group—receipt photo in, balances out.
• Event teams tracking expenses without spreadsheets—assign items by name and get instant bill requests.
• Automation engineers deploying a production-ready WhatsApp bot with OCR, messaging, and Sheets-based state.

Technical details

• Integrations: WAHA (WhatsApp webhook + media download + send), Google Gemini (receipt OCR extraction), OpenRouter (humorous bills + reminders), Google Sheets (Sessions, Contacts, Bills, status updates).
• n8n nodes/logic: if, set, code, merge, plus date-based scheduling for the 7 PM reminder run.