Gunjan Kumar
Available for full stack and backend-focused engineering roles

Backend-focused Full Stack Developer

Building production SaaS platforms with MERN Stack and Next.js.

Full Stack Developer with 2.5+ years of experience building production web applications, REST APIs, authentication systems, payment workflows, notification integrations, and responsive SaaS interfaces.

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About

I build full stack products where APIs, workflows, and interfaces work together cleanly.

I am a Full Stack Developer based in Hyderabad, India, with 2.5+ years of experience building and maintaining production web applications using MERN Stack and Next.js. My work spans SaaS platforms, automotive marketplaces, emergency QR systems, operational dashboards, payment subscription flows, notification systems, and deployment support.

I am strongest in backend-oriented full stack development: REST API architecture, JWT authentication, RBAC, middleware design, validation, error handling, MongoDB schema design, aggregation pipelines, indexing, cron jobs, and third-party integrations. I also build responsive frontend interfaces with React, Next.js, Redux Toolkit, Tailwind CSS, Ant Design, and Material UI.

I care about clean code, modular backend design, reliable workflows, and product features that are maintainable after launch. I am comfortable collaborating with product and engineering teams in Agile sprint cycles, debugging production issues, and contributing across frontend, backend, and deployment workflows.

Backend-focused full stack developer
Production SaaS and marketplace experience
Strong REST API and authentication background
Payment, notification, and automation workflow integrations
Comfortable with deployment support and production debugging

Full Stack

Frontend, backend, and APIs

Next.js

App Router architecture

MERN

MongoDB, Express, React, Node

Experience

Senior SaaS engineering timeline.

A role-based progression focused on full stack product delivery, scalable frontend systems, and reliable application architecture.

Aug 2024 - Present

Software Engineer - Full Stack MERN + Next.js

Fusionverse Autos Pvt. Ltd. formerly V2R Autoinfinite

01

Developing and maintaining production modules across VR Garage, VecRep, and ResqTag using React.js, Next.js, Node.js, Express.js, and MongoDB.

  • Built REST APIs with structured controllers, validation layers, middleware, and reusable backend modules.
  • Worked on Easebuzz eMandate payment subscription workflows, webhook integrations, and cron-based background processing.
  • Optimized MongoDB indexing and aggregation queries for dashboard and operational data processing.
  • Integrated WhatsApp Cloud API and IVR systems for automated transactional and emergency communication workflows.
  • Supported deployments using PM2, environment configuration, and production issue debugging.
  • Collaborated with product and engineering teams in Agile sprint cycles, feature planning, and code reviews.
VR GarageVecRepResqTagEasebuzzWhatsApp Cloud APIIVRPM2MongoDB

Jun 2023 - Jul 2024

Full Stack Developer MERN

Amunik Solutions Pvt. Ltd.

02

Built full stack web application features using React.js, Redux Toolkit, Tailwind CSS, Node.js, Express.js, MongoDB, and MySQL.

  • Built responsive frontend interfaces using React.js, Redux Toolkit, Tailwind CSS, and component-based architecture.
  • Developed backend APIs with Node.js, Express.js, MongoDB, and MySQL integrations.
  • Implemented AWS S3 file upload workflows and cron-driven background automation.
  • Integrated email, SMS, and WhatsApp notification services for operational systems.
  • Improved frontend rendering and API reliability through refactoring and debugging.
ReactRedux ToolkitAWS S3Cron JobsMongoDBMySQL

Case Studies

Production projects framed as engineering stories.

Each project is structured around the problem, solution, backend responsibility, product workflow, and architecture decisions.

01 / Live

ResqTag - Smart Emergency QR System

Emergency communication platform using secure QR-driven workflows and multi-channel alerting.

React.jsNode.jsMongoDBViteTailwind CSS

Problem

Emergency contact and alert workflows need to be fast, accessible, and reliable across devices, especially when users scan a QR code during urgent situations.

Solution

Developed a PWA-based emergency communication platform with secure QR-driven access, backend authentication, notification handling, and real-time emergency alert processing.

Key Features

  • QR-based emergency profile access
  • PWA-friendly user experience
  • Authentication and secure backend APIs
  • Real-time emergency alert processing
  • WhatsApp and IVR automation
  • MongoDB-backed emergency profile and alert data

02 / Live

VR Garage - SaaS Garage Operations Platform

Operational SaaS platform for garage workflow management, CRM, billing, staff management, and subscriptions.

React.jsRedux ToolkitNode.jsMongoDB

Problem

Garage operations require coordinated workflows across job cards, customers, billing, staff, permissions, and recurring subscription logic.

Solution

Developed production modules for garage operations with role-based access, backend APIs, reusable frontend patterns, billing flows, and cron-based automation.

Key Features

  • Job card management
  • CRM workflows
  • Billing modules
  • Staff management
  • RBAC authentication and permissions
  • Subscription billing workflows
  • eMandate integration
  • Cron-based background processing

03 / Live

VecRep - Automotive Service Marketplace

SEO-friendly automotive service marketplace with booking workflows and backend marketplace APIs.

Next.jsNode.jsMongoDB

Problem

Marketplace platforms need discoverable pages, fast loading, reliable booking flows, and backend systems that support operational transactions.

Solution

Built SEO-friendly pages and booking workflows using Next.js rendering strategies and backend marketplace APIs.

Key Features

  • SEO-friendly service pages
  • SSR/ISR rendering strategies
  • Booking workflow implementation
  • Marketplace API integrations
  • Backend operational transaction flows
  • MongoDB-backed service and booking data

Architecture

Workflow diagrams for the systems behind the screens.

Architecture callouts make the backend and operational complexity visible: auth, payments, notifications, rendering, and background processing.

VR Garage

SaaS Subscription Workflow

Payment workflows require webhook handling, failure states, renewal logic, and background processing.

Plan Selection/
API Validation/
eMandate/
Webhook/
MongoDB/
Cron Renewal/
Subscription State
  • Shows backend maturity beyond button-level integrations
  • Connects billing UX to reliable server-side state

ResqTag

Emergency Notification Pipeline

Multi-channel communication workflow for a time-sensitive emergency product context.

QR Scan/
Emergency Profile/
Alert API/
Contact Resolver/
WhatsApp/
IVR/
Alert Logs
  • Highlights backend routing and notification reliability
  • Demonstrates workflow design for urgent user journeys

VR Garage

RBAC Permission Model

Secure SaaS access control using token auth, role resolution, and module-level permissions.

JWT/
Auth Middleware/
Role/
Permission/
Protected Route/
Module Access
  • Demonstrates SaaS-grade authorization thinking
  • Maps backend middleware directly to product permissions

VecRep

Marketplace Rendering Strategy

SEO-oriented rendering strategy connecting discoverable pages, booking flows, and backend transactions.

SSR/
ISR/
SEO Pages/
Booking Flow/
Marketplace API/
MongoDB
  • Shows Next.js beyond basic page building
  • Connects frontend rendering choices to marketplace growth

Skills

Skills grouped by engineering capability.

The stack is organized around what each skill enables in production, not as a flat logo wall.

Frontend product systems

React.jsNext.jsRedux ToolkitTailwind CSSAnt DesignMaterial UIResponsive UI DevelopmentSSR and ISRSEO OptimizationComponent-based architecture

Backend and API architecture

Node.jsExpress.jsREST API DevelopmentJWT AuthenticationRBACMiddleware ArchitectureValidation and Error HandlingAPI SecurityModular Backend DesignMVC PatternsAPI Versioning

Data modeling and optimization

MongoDBMongooseMySQLSchema DesignAggregation PipelineQuery OptimizationIndexing

Payments, notifications, and workflow automation

Easebuzz eMandateRazorpayWhatsApp Cloud APIIVR APINodemailerCron JobsWebhooksSMS and email workflows

Deployment and production support

AWS S3Basic EC2PM2VercelDocker BasicEnvironment ConfigurationProduction issue debugging

Engineering workflow

GitGitHubPostmanCursorGitHub CopilotAI-assisted debugging workflowsAgile collaborationCode reviews

Highlights

Additional signals recruiters and engineering teams should notice.

Production-grade SaaS exposure

Worked on SaaS platforms, workflow automation systems, and marketplace applications with real operational complexity.

Backend-oriented full stack delivery

Built secure APIs, auth flows, notification systems, payment workflows, and MongoDB-backed application modules.

Deployment and debugging support

Familiar with PM2, Vercel, environment setup, deployment workflows, and production issue investigation.

Contact

Let's build product-grade web applications with clean backend systems.

Open to full stack, MERN, Next.js, and backend-focused SaaS roles where production reliability, API architecture, and workflow automation matter.

gunjan.mern@gmail.comDownload Resume