Hi! My name is Gaurav Kumar

I build scalable backend systems that power products used by millions.

Backend Developer with 5+ years of experience in building scalable SaaS products using Node.js, Express.js, React.js, and Next.js. Proficient in API development, microservices architecture, GraphQL, AWS, and cloud deployment. Led a team of 5 engineers, reduced system latency by 40%, and handled 1L+ notifications monthly. Strong focus on delivering robust solutions in agile environments.

Skills

Backend

Node.jsExpress.jsNest.jsGraphQLREST API

Frontend

React.jsNext.jsTypeScriptJavaScriptTailwind CSS

Database

PostgreSQLMongoDB

Cloud & DevOps

AWSDockerCI/CD

Tools & Other

RabbitMQSalesforceGit

Experience

API Lead

Twimbit

Jan 2023 - Present
  • Directed the development of a scalable notification service for Twimbit Vault using RabbitMQ, enhancing customer engagement and reducing system latency
  • Architected and implemented a multi-tenant SaaS platform using microservices, Node.js, Docker, and AWS (EC2, S3, RDS) to ensure secure, automated cloud deployment and operational efficiency
  • Led a team of 5 engineers to design and implement an in-house CMS with Next.js + GraphQL APIs (Node.js backend) supporting editor-based publishing workflows, actively used by ~1K users per tenant in production
  • Integrated Salesforce CRM support in Vault CMS to sync leads and contacts seamlessly across tenants and expose GraphQL endpoint for chatbot integration
  • Developed a GraphQL-based data integration system that optimised API performance and minimised response times
  • Mentored junior developers by conducting code reviews and providing guidance on best practices in API design, microservices, and cloud deployment
Node.jsGraphQLNext.jsRabbitMQDockerAWSSalesforceSaaSReact

Back-end Developer

Twimbit

Apr 2020 - Dec 2023
  • Developed GraphQL APIs for the user feed, enabling efficient content delivery and personalized queries for end users
  • Connected user reactions to the feed pipeline to drive engagement-based content ranking
  • Implemented a subscription gateway integrating Stripe for subscription billing and payment processing
  • Federated multiple microservices into a single GraphQL API, improving developer experience for front-end teams
  • Added an organization-level payment system, allowing an org admin to provide platform access to the entire team through a single payment
Node.jsGraphQLDockerAWSRedisMongoDB

Software Intern

Twimbit

Jan 2020 - Apr 2020
  • Contributed as a Full Stack Engineer by resolving front-end bugs, refactoring legacy components, and implementing new UI designs in React to enhance usability
  • Implemented design improvements in React to boost user experience and maintain front-end consistency
  • Implemented an Invitation service using Node.js and Express.js that lets admin invite users to the platform via invitation link
ReactNode.jsExpress.jsNext.js

Software Development Engineer

Bridged Media

Nov 2019 - Dec 2019
  • Migrated a legacy REST API to GraphQL in Nest.js architecture to improve client-side data fetching and overall system performance by 35%
  • Implemented JWT-based authentication while integrating SQL (PostgreSQL) and NoSQL (MongoDB) databases to support diverse data models
  • Built a feature to filter popular posts using view events, improving content discovery and user engagement
Nest.jsGraphQLPostgreSQLMongoDBJWTREST API

GraphQL API Developer

Vieuth™ - View of Youth

Oct 2019 - Nov 2019
  • Designed and developed a comprehensive full-stack web application using MERN stack to facilitate students' academic journeys, including task management and opportunities application
  • Architected the system using a GraphQL API to seamlessly connect multiple services for enhanced functionality
  • Implemented a payment system with coins for task completion and redemption
  • Created reporting service for mentor performance reports and shareable student report cards
MERNGraphQLNode.jsExpress.jsMongoDBReact

Back End Developer

Hajaam

Aug 2019 - Sep 2019
  • Developed backend for salon appointment booking platform with automated calendar invites
  • Built rating/review system enabling top salon filtering based on popularity
  • Created REST APIs with TDD achieving 99.9% test coverage, reducing production bugs
  • Automated AWS deployments with CI/CD, improving release speed by 30%
Node.jsExpress.jsAWSCI/CDTDDREST API

Full Stack Engineer

Young Engine™

Apr 2019 - Jul 2019
  • Built full-stack application connecting students with companies for short-term tasks
  • Implemented features: task creation/verification, submission, reward allocation, authentication, profile management
  • Developed wallet system for rewards upon task completion using MERN stack
MERNNode.jsExpress.jsMongoDBReact

Projects

Postgres Agent (LangChain + Ollama)

A working example agent that queries PostgreSQL using LangChain and Ollama, showing an end-to-end local AI workflow with no paid API dependency.

PostgreSQLLangChainOllamaNode.js
Agent-based PostgreSQL querying using natural language
Uses LangChain orchestration with a local Ollama model
Demonstrates a free, local-first AI + database integration pattern

AI-Powered Shopping Assistant

A conversational shopping assistant that lets users browse products, add to cart, and checkout using natural language AI search.

Next.jsVercel AI SDKTailwindGraphQL
Conversational AI interface for product search
Cart management & checkout flow
Gemini-powered natural language queries

Crypto Wallet with MetaMask

A Web3 wallet application enabling users to connect MetaMask, view balances, and send transactions on Ethereum testnet.

Next.jsEthereumWeb3MetaMask
MetaMask wallet integration
Transaction history dashboard
Sepolia testnet support

Real-time Notification Service

Scalable microservices-based notification system handling millions of messages with RabbitMQ and AWS. Supports multi-channel delivery (email, push, SMS) with queuing and retry mechanisms.

Node.jsRabbitMQAWS (EC2, S3, RDS)Docker
Multi-channel notifications: email, push notifications, SMS
Message queuing with RabbitMQ for reliable delivery
Reduced system latency by 40% through optimization
Microservices architecture deployed on AWS with auto-scaling
Handles 1 lakh+ (100K+) notifications monthly with 99.9% uptime

Enterprise CMS Platform

Multi-tenant SaaS CMS with GraphQL APIs supporting editor-based publishing workflows. Integrates with Salesforce CRM for lead management and serves ~1,000 users per tenant.

Next.jsGraphQLNode.jsSalesforceAWS
Multi-tenant architecture with isolated data per tenant
GraphQL API with optimized resolvers for fast queries
Salesforce CRM integration for lead & contact sync
Editor-based publishing workflows for reports
Production-ready with ~1K active users per tenant

Blog