I build production systems that stay fast when real users arrive.

Building APIs, attribution systems, CRM synchronization, and production reliability improvements for a platform serving 10,000-20,000 daily active users.

• Built RESTful APIs with NestJS and Java Spring for campaign and reward workflows.
• Implemented attribution tracking with device fingerprinting and Google Install Referrer.
• Integrated Salesforce CRM with custom field mappings and real-time synchronization.
• Optimized PostgreSQL queries through indexing, refactoring, and Redis caching.
• Fixed critical reward redemption race conditions and added Jest plus k6 verification.
• Handled Flutter iOS and Android build delivery with consistent release output.

Contributed backend APIs for a sport venue booking platform with authentication, maps, deep-link attribution, payments, and production deployment workflows.

• Developed backend APIs using NestJS, Prisma, and PostgreSQL.
• Implemented JWT authentication, location search with mapping integration, and deep-link attribution.
• Integrated VNPay, MoMo, and ZaloPay with webhook handling and transaction reconciliation.
• Gained production experience in REST API design, ORM patterns, and deployment workflows.