Bablu Kumar Singh

System Implementation Portfolio

Explore production engineering case studies mapping system design architectures, database designs, and performance optimizations.

ROI Spectrum
SaaS Platforms

ROI Spectrum

Node.jsExpress.jsPostgreSQLMongoDBReact.jsStripeRedis

The Problem: SEO agencies and website owners lacked an integrated, multi-tenant solution to track ROI, audit logs, service tracking, and automated subscription billing transparently.

The Architecture: Multi-tenant database schema architecture using Node.js/Express backend, React.js frontend, and hybrid storage using PostgreSQL for relational billing data and MongoDB for audit logs.

The Results: Successfully deployed and launched the platform at roispectrum.com, handling hundreds of active tenants, reducing query response times by 30% through composite indexing, and fully automating subscription operations.

Forklift CRM
CRM Applications

Forklift CRM

Node.jsExpress.jsMongoDBReact.jsSocket.ioZod

The Problem: Operations managers struggled to handle lead assignments, track workflow automations, and manage sales representatives with clean role-based permissions.

The Architecture: Full stack architecture with an Express.js REST API using MongoDB for dynamic lead schemas and Next.js/React frontend with complex dashboard states.

The Results: Deployed a CRM system that streamlined lead workflow automation, eliminated manual assignment delays, and handled real-time updates via WebSockets with zero downtime.

High-Throughput API Gateway
Backend Systems

High-Throughput API Gateway

Node.jsExpress.jsRedisDockerJWTNginx

The Problem: Microservices suffered from erratic traffic spikes, lack of centralized token validation, and rate-limiting issues that degraded downstream systems.

The Architecture: Custom proxy server built with Node.js, Express, and Redis Cluster, acting as a reverse proxy, rate limiter, and JWT authenticator.

The Results: Centralized routing for 5 microservices, maintaining sub-10ms response latencies while shielding database clusters from denial-of-service traffic.