Automate Daily WhatsApp Reminders

I keep all client details—name, phone number, current outstanding balance anddue date—in a Google Sheet. Every day I want a small service to scan that sheet, pick out anyone whose balance is above zero, merge their data into the WhatsApp message template I already use, and send it through my own WhatsApp Business (Cloud) API endpoint.

Key points you should know:
• Data source is a spreadsheet, not a full CRM.
• The wording of the reminder is already final; your job is to insert the variables and dispatch it.
• Transmission must happen via a custom API call, not a third-party bulk platform.

Deliverables
1. A script or micro-service (Python, Node.js or similar) that:
– Pulls the sheet once per day at a scheduled time I can change.
– Generates personalised messages using my template.
– Sends each message through my WhatsApp API endpoint and captures the API response.
– Writes a “last sent” timestamp back to the sheet so the same client is contacted again only if the balance still exists on the next run.
2. Clear setup instructions so I can deploy the job on my own server, VPS or a cloud function.
3. One brief hand-over call or document explaining how to adjust the message text, scheduling time and API credentials.

Acceptance criteria:
• All clients with an outstanding balance receive one WhatsApp per day until their balance is cleared in the sheet.
• No client receives duplicate messages on the same day.
• Error logs identify any failed deliveries and leave the row untouched for the next run.
• Solution runs reliably for seven consecutive days in test before sign-off.

If you’ve connected spreadsheets to WhatsApp APIs before, or have existing libraries that streamline the process, please let me know—ready to get this running quickly.