Monish Khambalkar

Full Stack Developer with 4+ years of experience building scalable web applications end-to-end using React.js, Redux, Node.js, Express.js, NestJS, MongoDB, Redis, AWS, and Docker. Experienced in designing REST APIs, NestJS microservices (subscription billing, notification, payment integration), real-time systems, and cloud deployments across healthcare and e-commerce domains. Earlier in my career, also worked on enterprise PHP applications.

Full Stack Developer (React.js | Node.js | NestJS) at Plus91 Technologies Pvt. Ltd. (2022-04 – Present)

Building scalable full stack applications and microservices for healthcare and e-commerce platforms — frontend, backend, cloud deployment, and performance optimization.

Pharmacy & Multi-Vendor Inventory Management Platform at Plus91 Technologies Pvt. Ltd. (2022-04 – Present)

Scalable pharmacy and multi-vendor platform for inventory, product catalog, vendor management, authentication, and order workflows.

• Designed 40+ secure REST APIs for product, inventory, vendor, and user management, including payment gateway and WhatsApp Business webhook integrations for order/delivery notifications.
• Developed reusable, responsive React.js components using custom hooks, React Router, Context API, lazy loading, and memoization, improving front-end load performance by nearly 35%.
• Implemented JWT authentication, Redis caching, centralized error handling, and API security best practices, improving API response times by up to 40%.
• Built independent NestJS microservices for subscription billing, notification service, and payment integration, decoupling these workflows from the core monolith for independent scaling and deployment.
• Integrated third-party notification channels — WhatsApp Business API and email — into the NestJS notification service for real-time order and delivery alerts.
• Built asynchronous Excel bulk-upload processing using worker threads and improved scalability using Node.js Cluster for large product datasets.
• Containerized Redis and PDF-generation services with Docker; automated AWS (EC2, S3, Load Balancer) deployments via Jenkins CI/CD, cutting release time by nearly 50%.
• Investigated and resolved 60+ production issues, improving backend performance and maintainability.
• Developed unit tests using Jest, improving backend code coverage and reliability.

Multi-Vendor E-Commerce Platform at Personal Project

Self-initiated subscription-based multi-vendor marketplace enabling vendors to list and sell products under tiered subscription plans, with integrated payments, analytics, and real-time support.

• Built subscription-based vendor onboarding with tiered plans, controlling vendor access to product limits, storefront features, and payment settlement cycles.
• Designed and integrated a payment module supporting vendor subscription billing and customer checkout, with webhook-driven order and payment status updates.
• Developed a vendor dashboard with product upload, inventory tracking, and an automated profit & loss report per vendor, aggregating sales, cost, and margin data.
• Rebuilt the subscription billing, notification, and payment modules as standalone NestJS microservices, enabling independent scaling and deployment from the core marketplace API.
• Integrated WhatsApp and email as third-party notification channels into the NestJS notification microservice for order updates, low-stock alerts, and subscription renewals.
• Built a WebSocket-based tech-support chat application for real-time buyer-vendor and buyer-support communication, backed by Redis for session and presence management.
• Scheduled cron jobs for subscription renewal checks, vendor billing cycles, and stale-cart/order cleanup.
• Applied a circuit breaker pattern around third-party payment and notification calls to prevent cascading failures during upstream outages.
• Used PM2 for process management and Node.js clustering to utilize multiple CPU cores, and load-tested critical APIs to validate throughput before scaling.
• Applied core system design principles — service separation, caching layers, and queue-based decoupling — to keep the platform maintainable and horizontally scalable.

Hospital Management System (HMS) at Plus91 Technologies Pvt. Ltd.

Enterprise healthcare platform (patient registration, OPD/IPD, billing, pharmacy, appointments). Developed 25+ REST APIs and backend modules, designed a microservice-based Tax Calculation service, optimized MySQL reporting queries by ~75% (1.8s → 400ms), and resolved 50+ production issues — improving overall application performance by nearly 30%.

Bachelor of Commerce in B.Com – Rashtrasant Tukadoji Maharaj Nagpur University (RTMNU) (2018-06)