Overview
This work combined backend API design, business-rule implementation,
data workflows, ERP core-system design, and targeted interface
improvements across multiple products. The common thread was
production delivery: shipping features that solve real operational
problems for users and teams.
In addition to the public-facing items below, the broader freelance
scope also included private client work related to delivery-service
workflows and system customization.
Core stack
- Go
- Gin
- MySQL
- Redis
- PHP
- Laravel
- Angular
- Spring Boot
- PostgreSQL
- Docker
- Keycloak
- REST APIs
Trading platform
Go, Gin, MySQL, Redis
User-to-user buying and selling platform
Backend system for product trading with wallet-based payment flow,
seller controls, buyer order actions, and automated order handling.
- Built APIs for listing, buying, and selling products with status tracking.
- Implemented automatic unpaid-order cancellation using Redis.
- Added seller-side CRUD and order management capabilities.
- Enabled buyer-side receive, cancel, and payment actions.
- Created transaction logs covering refunds, order cost, and cancellations.
- Implemented user collections for saved products.
Media platform
Go, Gin, MySQL
Comics and short-video platform
Backend work for a content platform supporting browsing, filtering,
playback, subtitles, history tracking, and user collections.
- Developed APIs for browsing and filtering comics and videos.
- Enabled subtitle-aware playback and detailed content views.
- Tracked user viewing and reading history.
- Implemented content collections for easier access to favorites.
ERP core system
Bol.com marketplace integration
Angular, Spring Boot, PostgreSQL
Custom ERP Core System with Marketplace Integration (Bol.com)
Designed and developed a custom ERP core system integrating
inventory, finance, forecasting, and marketplace data into one
operational workflow.
- Implemented stock management, accounting, cashflow forecasting, and margin calculation modules.
- Integrated with the Bol.com Retailer API for automatic product, price, and commission synchronization.
- Built automated scheduler processes for data sync, forecasting, and financial calculations.
- Developed finance features covering balance, profit and loss, VAT, tax payments and receipts, auto-accounting, and snapshots.
- Implemented forecasting logic using historical and predicted sales data for stock and cashflow planning.
- Created automated workflows for stock planning, cashflow prediction, and accounting operations.
- Implemented role-based access, email notifications, background job processing, and flowchart-based business workflow design.
ERP system
Laravel, MySQL, JavaScript
ERP enhancements and POS improvements
Full-stack work on ERP features, financial reports, POS behavior,
stock calculations, and usability improvements across business forms.
- Added financial reports with Excel import and export support.
- Implemented discounts across SI and POS sales flows.
- Improved POS sales forms and print slips with discount details.
- Added points-management features for SI and POS transactions.
- Delivered stock reports with reorder calculations based on activity and thresholds.
- Fixed bugs and improved overall system behavior and interface quality.
Architecture
Microservices and gateway
Microservices and API gateway refactoring
Refactored existing REST APIs into a microservices-oriented setup to
improve scale, maintainability, and service separation.
- Moved product-related CRUD APIs into service boundaries.
- Implemented operation-record management APIs.
- Created Excel-based import and export templates for data handling.
- Delivered supporting email services and dictionary APIs.