EZOO POS System
POS and inventory backend built for Rayon Energy, a solar equipment and electrical supplies company, focused on financial accuracy, stock management, and asynchronous operations using FastAPI and PostgreSQL.
Source CodeOverview
Repository: GitHub - M-Alhbyb/ezoo_pos
EZOO POS is a backend-focused point-of-sale and inventory system built for Rayon Energy, a company specializing in solar equipment and electrical supplies.
The system was developed using FastAPI with asynchronous database operations to support scalable performance and concurrent usage scenarios.
A major focus during development was preventing financial precision issues by using Decimal arithmetic instead of floating-point calculations.
The project includes inventory management, transaction processing, fee calculations, VAT support, immutable sales records, and structured validation using Pydantic schemas.
The backend architecture emphasizes explicit business rules, data consistency, maintainability, and backend authority over calculations and validations.
Architecture
Modular FastAPI architecture with separated API, schema, model, and service layers. PostgreSQL as the primary source of truth for inventory and financial operations. Async SQLAlchemy integration using asyncpg. Alembic migration system for schema versioning. Decimal-based financial calculations for transaction precision. WebSocket-ready architecture for future real-time POS synchronization.
Challenges
Preventing floating-point precision errors in financial workflows. Designing immutable transaction workflows suitable for audit trails. Maintaining data integrity during asynchronous operations. Structuring reusable calculation systems for fees and VAT handling.
Deployment
Backend-first architecture focused on reliability and maintainability. Built using PostgreSQL and Alembic for long-term schema consistency. Designed with scalability and testability as core priorities.
Outcomes
Built a production-oriented backend suitable for retail systems. Implemented reliable financial calculation workflows using Decimal precision. Established scalable API architecture for future expansion.