Sumit Kumar
Full Stack Developer · Backend & Real-Time Systems

India
LinkedIn: imsumit45
Email: ersumitkumar45@gmail.com

Full Stack Developer focused on building scalable web applications with strong backend architecture, real-time systems, and production-oriented engineering practices.

• Data Structures & Algorithms
• System Design fundamentals
• Distributed systems concepts
• Scalable backend architectures

Live: https://curlix.vercel.app/
Scalable URL shortener platform built for production.

Highlights

• Redis-first redirect architecture for fast lookups
• Queue-based analytics using BullMQ
• Async event handling for non-blocking redirects
• Anonymous ownership with bearer tokens
• Rate limiting, abuse prevention, and SSRF-safe URL validation
• Free infrastructure stack

Tech Stack
React · Node.js · Express · PostgreSQL · Supabase · Redis · BullMQ · Upstash · Vercel · Render

Live: https://paperpilot2026.vercel.app

AI-powered assessment generation platform that creates structured question papers, answer keys, and printable PDFs using an asynchronous worker architecture.

Highlights

• AI-generated question papers powered by DeepSeek LLM
• Queue-based paper generation using BullMQ and Redis
• Real-time generation progress via Socket.io
• Automatic Zod validation with retry-on-failure pipeline
• PDF generation with Redis caching for faster downloads
• Monorepo architecture with shared type-safe contracts

Tech Stack
Next.js · React · Tailwind CSS · Express · MongoDB · Redis · BullMQ · Socket.io · PDFKit · Zod · OpenAI SDK (DeepSeek) · pnpm Workspaces

Live: https://collabdocs2026.vercel.app

Real-time collaborative document editor with an AI writing assistant and Word-compatible import/export.

Highlights

• CRDT-based real-time editing with Yjs, synced over Socket.io using a Redis adapter for multi-instance scaling
• AI writing assistant (DeepSeek LLM) with streaming responses and per-user rate limiting
• Rich text editing: tables, task lists, code blocks with syntax highlighting, math equations, mentions, and inline comments
• Document version history, notifications, and folder-based organization
• Import from Word (.docx) via Mammoth; export to DOCX/PDF
• Google OAuth + JWT auth, with Helmet and rate limiting for API security

Tech Stack
Next.js · TypeScript · Tailwind CSS · Express · Socket.io · Yjs · MongoDB · Redis · Tiptap · Mammoth · docx · PDFKit · DeepSeek (OpenAI SDK) · JWT · Passport (Google OAuth) · Helmet · Swagger · Jest · Playwright · ESLint

Live: https://notifyx-sumit.vercel.app/

Notification system backend built with a distributed worker setup.

Highlights

• Producer-worker architecture with BullMQ and Redis
• Real-time delivery via Socket.io
• Offline sync for missed notifications
• Two-layer idempotency to prevent duplicate deliveries
• JWT auth on REST routes and Socket.io handshakes
• Role-based access control at middleware level

Tech Stack
Node.js · Express · React · MongoDB · JWT · Socket.io · BullMQ · BullBoard · Redis

Live: https://devconnect2026.vercel.app

Developer social platform with auth, messaging, and real-time features.

Highlights

• Secure authentication with 2FA, OAuth, and JWT sessions
• REST APIs for posts, messaging, notifications, and analytics
• WebSocket-based real-time notifications
• Modular backend with clean routing and middleware flow

Tech Stack
React · Node.js · Express · MongoDB · Socket.io · JWT · Bcryptjs · OAuth · 2FA (TOTP) · CORS · node-cron · Cloudinary · Multer · qrcode · Helmet · ESLint

React · Next.js · TypeScript · Tailwind CSS · JavaScript · CSS

Node.js · Express.js · REST APIs · WebSockets (Socket.io) · JWT Authentication

LLM Integration · Prompt Engineering · OpenAI SDK · DeepSeek · Zod

MongoDB · Mongoose · PostgreSQL · Redis · Supabase

BullMQ · Distributed Systems · Queue-based Architectures · Real-time Event Processing · Idempotency Patterns

JWT · Bcryptjs · OAuth (Google/GitHub) · 2FA/TOTP · Helmet · CORS · Rate Limiting

Git · Node-cron · Cloudinary · Multer · PDFKit · Vercel · Render · Railway · Upstash · Postman · ESLint · pnpm Workspaces

B.Tech in Computer Science
Vellore Institute of Technology (2024 – 2028)

Certifications & Courses

• Applied Machine Learning in Python (Coursera) — University of Michigan (2025)

• Data Structures & Algorithms
• System Design and distributed systems
• Low-level design patterns
• Performance engineering and scalability

Have a project idea or want to collaborate? Reach out:

• Email: ersumitkumar45@gmail.com
• LinkedIn: https://linkedin.com/in/imsumit45
• GitHub: https://github.com/imsumit28