Built and maintained high-performance RESTful APIs with NestJS and TypeScript, handling over 500K requests per month across multiple services. Optimized PostgreSQL, MongoDB, and Redis schemas, reducing average API response times by up to 40% through strategic indexing and caching. Implemented secure, scalable authentication using JWT and Google OAuth2, enabling cross-platform login for 5+ integrated systems. Integrated critical third-party services, including WhatsApp API, Iris Payment, Firebase Notifications, and Gmail API, enhancing system interoperability. Developed real-time notification and background task systems with Redis queues, increasing asynchronous task throughput by 60%.

Developed an interactive WhatsApp bot that processed up to 100K messages daily, significantly improving user engagement through chat automation. Integrated a payment gateway for digital rewards, supporting 5+ incentive programs with seamless transaction flow. Built and maintained RESTful APIs powering 10+ web and mobile apps, ensuring performance and reliability at scale. Streamlined internal development workflows, doubling annual project delivery from ~5 to 10+, while reducing third-party vendor reliance and cutting development costs.

Designed and developed multi-tenant admin APIs with NestJS, TypeScript, and Keycloak integration (OAuth2). Built tenant registration, session management, and RBAC-based auth endpoints with secure middleware and JWT guards. Structured MongoDB schemas for tenants, users, and logs in a scalable architecture. Added activity logging for critical actions to support audits and compliance. Documented APIs with Swagger.