Challenge
No system for managing sales and payments. The company was managing everything through WhatsApp messages and basic spreadsheets. They had no centralized system to track which lots were sold, monitor customer payments, manage installment plans, or send payment reminders. This created operational chaos: lost payment records, missed collections, no visibility into cash flow, and constant manual work to figure out who owed what. With hundreds of customers paying monthly installments and maintenance fees, the lack of organization was becoming a serious business problem.
Action
Built a complete management system. Built a complete web application for all business operations. Manages customers, lot sales, payment tracking, legal invoicing, and automated communications.
UI/UX Design
Complete Figma design with light and dark themes. Complex tables, nested views, and real-time metrics made accessible for non-technical staff. Careful data organization across all sections. One click on any row and access complete customer details: lots, payments, invoices, maintenance history.
Customer and sales management
All customer data, lot assignments, and purchases tracked in one place. Sales can be set as full payment or installments. Installment plans autogenerate complete payment schedules with due dates. Customer profiles display all lots, payments, invoices, and maintenance in detailed views.
Automated payment tracking
Automatic tracking for all payment schedules. Late payments flagged immediately with real-time calculation of days overdue. Dashboard shows expected income, total revenue, installments, and delinquency rate. All metrics auto-calculated and filterable by date.
Legal invoice generation with SUNAT integration
Customer payments trigger automatic invoice generation with full SUNAT compliance. Digitally signed XML, QR codes, and complete tax documentation included. Instant generation, team sends via WhatsApp. Most complex feature since SUNAT has no official API. Required third-party integration and handling all compliance requirements.
Automated maintenance billing
Monthly maintenance charges autogenerate for all lot owners every month. Advance payments supported. Pay six months ahead and the system records it, skipping automatic charges for those months. Month-by-month filtering shows payment status.
Automated SMS reminders
Daily automated SMS to overdue customers via Twilio. Replaces manual follow-up, ensures consistent reminders without staff involvement.
Problems while building
Two things made this harder than a typical CRUD app: a government tax system with no public API, and payment logic complex enough to demand careful design.
SUNAT integration without official API
The hardest part of the entire build — not the code itself, but integrating with a government system that has no public API, no sandbox, and strict, largely undocumented formats. Signed XML, QR codes, and evolving tax compliance all required. Reliability came from extensive testing against real invoices and debugging edge cases one by one.
Complex business logic
Overlapping payment schedules: lot installments, maintenance, advance payments, late tracking, automatic invoicing. Everything stays synchronized. Multiple lots per customer, each with own plan plus maintenance. Complex calculation logic for dues, payments, overdue status, and invoice generation to prevent errors.
Result
Transformed business operations, replacing WhatsApp and spreadsheet chaos with complete visibility and control. First two weeks post launch, owners were thrilled to finally see everything in one place. Their words: "What you can't measure, you can't improve." Automated tracking, instant invoicing, and daily reminders eliminated manual work and boosted collections. Real-time dashboard shows cash flow, delinquency, and revenue previously invisible. Manages hundreds of customers with concurrent payment schedules, impossible manually without errors.