AppSheet / Google Sheets Developer for CRM + Quotation + Sales KPI System Budget 40-70 $ Delivery time within 7 days

Project Description:
We are a premium windows & doors company based in Thailand (MODA Windows & Doors),
and we are looking for an experienced developer to build a complete business management system
using Google Sheets + AppSheet.
Main Objective:
Create a system that manages the full process:
Lead → Customer → Quotation → Follow-up → Closing → Invoice → Receipt → Installation →
Reporting
Core Features:
1. Customer Management
2. Quotation System with multiple items and sqm pricing
3. Discount Control (admin approval required if exceeded)
4. Sales Pipeline (Lead to Closed Won/Lost)
5. Sales Activity Tracking (calls, leads, meetings, visits)
6. KPI System (1,600,000 THB monthly target per salesperson)
7. Invoice & Receipt system
8. Project tracking (installation, warranty)
9. Photo upload system
10. Real-time dashboards and alerts
Technical Requirements:
- Google Sheets + AppSheet
- Strong logic, automation, and conditional fields
Developer Requirements:
- Proven AppSheet experience
- CRM or sales system background
- Business understanding mindset
Deliverables:
- Fully working system