Hao Jie Chang

-Took ownership of backend architecture using .NET/C# with ABP Framework, implementing layered design (BFF → Domain → Integration Agents) and delivering RESTful & GraphQL APIs in a multi-tenant SaaS environment. -Designed and implemented volume-based Work Order reporting and dynamic invoice/quotation PDF generation, owning end-to-end logic from frontend document templates to backend data aggregation.

-Led frontend engineering team in developing enterprise SaaS platforms Lessen Pro for Lessen (US-based PropTech company). -Architected and delivered Pro Success Hub (Admin Panel) enabling internal operations management, vendor oversight, and business workflow orchestration across the SaaS ecosystem. -Designed scalable UI architecture using React (TypeScript), MUI, JoyUI, Apollo GraphQL, enforcing reusable component systems and domain-driven folder structures. -Re-architected system by removing Qiankun micro-frontends and upgrading Webpack v4 → v5, significantly improving build speed, runtime performance, and maintainability. -Implemented end-to-end Stripe billing & subscription lifecycle management, including payment flows, subscription state transitions, webhook processing, and error handling. -Integrated QuickBooks Online (OAuth-based) to automate invoice synchronization and financial data reconciliation for vendor accounting systems. -Led agile delivery within SCRUM framework using JIRA, coordinating closely with Product, Design, and Backend teams to ship production-ready features at high velocity. -Mentored frontend engineers, conducted technical reviews, and established coding standards to ensure maintainable and scalable frontend codebase.

Work in the field of web application development and R&D