Naveen Raja
Verified Expert in Engineering
Lead Full-stack Developer
Chennai, Tamil Nadu, India
Toptal member since October 25, 2022
Naveen is a senior back-end engineer and certified solutions architect with 9+ years of experience building high-scale distributed systems and fintech platforms. He specializes in designing low-latency APIs, real-time systems, and cloud-native architectures that process millions of transactions reliably and efficiently.
Portfolio
Experience
- Python - 9 years
- JavaScript - 7 years
- Node.js - 7 years
- Java - 7 years
- React - 6 years
- Kubernetes - 6 years
- Groovy - 4 years
- Go - 2 years
Preferred Environment
Python, JavaScript, Node.js, React, FastAPI, Docker, Kubernetes, Go, Fiber, PostgreSQL
The most amazing...
...project I’ve built is Express Checkout, a scalable payment system handling millions of daily transactions with a fault-tolerant and low-latency architecture.
Work Experience
Lead Software Engineer
Freelance Clients
- Delivered an end-to-end back-end architecture for multiple international clients across fintech and SaaS domains, focusing on scalability and reliability.
- Designed and implemented high-performance APIs and distributed systems using Python, Go, and cloud-native technologies.
- Collaborated directly with stakeholders to translate business requirements into production-grade systems, reducing time-to-market and improving system stability.
- Led multiple client engagements involving system design and performance optimization for high-scale applications.
Lead Back-end Engineer
AB-InBev - Gen AI - India
- Led back-end architecture and development for CatExpert, a category management and retail analytics platform adopted by Walmart, 7-Eleven, and other major retailers.
- Led back-end development across 25+ microservices spanning planogramming, assortment, KPI analytics, and AI imagery.
- Architected and developed a reusable multi-user real-time collaboration framework using WebSockets, Redis Streams, and Redis Pub/Sub, powering the planogram canvas editor, spreadsheet editor, and PDF editor with many concurrent users per workspace.
- Re-engineered EDA pipelines from pandas to Polars LazyFrames with streaming execution and predicate pushdown, cutting runtime on the largest key accounts from 10–15 minutes to under one minute (about 15x faster) and reducing peak memory usage from about 20 GB (OOM) to roughly 600 MB (about 97% reduction).
- Rolled out KEDA-based autoscaling across all event-driven workers, cutting overall compute cost by around 30% alongside the Polars rewrite.
- Built a hierarchical folder-based workspace, a KPI dashboard computing 30+ KPIs in parallel across thousands of planogram experiments, and an AI-imagery module generating on-demand product images for planograms.
Lead Back-end Engineer
Picom Technologies
- Designed and led the back-end architecture for autonomous calling, AI conversations, campaign workflows, and customizable mission-based call flows, scaling to over 100,000 calls.
- Built real-time voice processing supporting live call takeover, AI voicemail handling, voice cloning, live notifications, call transcription, and AI-generated summaries.
- Built and managed AWS and Kubernetes infrastructure for distributed voice-processing services, including cluster setup, container orchestration, CI/CD automation, and scalable low-latency call handling.
Lead Software Engineer
Zid
- Architected and led development of ZidWallet with virtual IBAN support, payments, settlements, refunds, COD collections, and merchant balance management while safely migrating 15+ million legacy ZidShip transactions.
- Built a comprehensive back-office platform for finance and operations, merchant onboarding, KYC verification, transaction monitoring, treasury management, disputes, and regulatory compliance.
- Designed and built gRPC-based wallet back-end services for financial operations, and set up CI/CD pipelines using GitHub Actions, Docker, and Kubernetes for automated, scalable delivery.
Senior Software Development Engineer
Razorpay
- Migrated core systems from a PHP monolith processing 30+ million payments per day and $75+ billion annualized TPV to microservices handling peak traffic of 20,000+ RPS.
- Led the zero-downtime migration from monolith to microservices using feature-controlled rollouts and gradual traffic shifting.
- Built Instant Settlements, enabling merchants to receive payouts within seconds instead of the standard T+2 cycle, via both on-demand and automated real-time settlement flows.
Senior Software Development Engineer
Juspay Technologies Pvt
- Spearheaded back-end development of Express Checkout, a payment orchestration platform operating at a scale of 100+ million payments per day, $1+ trillion annualized TPV, peak 30,000+ RPS, with sub-200 ms latency and 99.999% SLA reliability.
- Engineered seamless checkout and DOTP (Direct OTP) for card payments, along with a unified single-click wallet experience through deep-linking and tokenized wallet integrations, improving transaction success rates by 7–8%.
- Built the card locker and re-architected it for RBI-mandated issuer tokenization, safely migrating 20+ million cards to tokenized flows.
- Developed a dynamic gateway routing engine that safely executed merchant-defined routing logic in sandboxed environments.
- Integrated 30+ payment gateways and aggregators, streamlined onboarding for new integrations, contributed to the merchant dashboard front end, and built merchant SDKs in Python, Java, and JavaScript.
Experience
CatExpert
https://catexpert.ab-inbev.com/As Lead Back-end Engineer, I architected and built the back-end systems powering the planogram and core platform features. I designed scalable services to handle large, hierarchical datasets and implemented real-time capabilities for collaborative editing. I developed foundational systems, including folder structures and centralized libraries, for product and image management. I also optimized performance by reducing memory usage and resolving critical bottlenecks, ensuring stability at scale, and enhancing CI/CD pipelines to improve deployment reliability and developer efficiency.
ZidWallet
https://zid.saIn my role as the technical lead, I orchestrated the architecture and development of the merchant wallet, complemented by an intuitive admin dashboard catering to essential back-office functions. The solution was crafted as a robust gRPC application using Django (Python) and a PostgreSQL database, harnessing the power of cutting-edge technologies such as AWS, Kubernetes, Redis, Celery, Locust, Datadog, and Sentry.
Express Checkout
https://juspay.io/in/expresscheckoutAs the project's lead developer, I wrote Express Checkout in Grails (Groovy) with a MySQL database. It leveraged several technologies, such as AWS, Redis, Nginx, Quartz, StatsD, Kibana, and Grafana. It was later rewritten in Node.js.
ZidWallet | Back-office Portal
https://zid.saDropcall
https://dropcall.app/As the lead developer, I spearheaded the design, development, and deployment of this innovative application. Built using Django, PostgreSQL, Firebase, AWS, Kubernetes, Celery, and Redis, the app leverages cutting-edge AI technologies, including GPT and Gemini, to deliver a natural and engaging communication experience.
Card Locker
https://juspay.in/productsIt was written in Grails (Groovy) with a MySQL database and AWS for cloud infrastructure.
Express Checkout Demo
https://bitbucket.org/juspay/ec-demoEducation
Bachelor's Degree in Information Technology
SSN College of Engineering - Chennai, India
Certifications
AWS Certified Solutions Architect – Professional
AWS
Skills
Libraries/APIs
Node.js, React, Socket.IO, Quartz, REST APIs, Amazon EC2 API, Sockets, Python API, React Router, React Redux, Pydantic, SQLAlchemy, API Development, Stripe, Protobuf, Python Asyncio, Asyncio, Twilio API, CyberSource, Pandas
Tools
Amazon CloudFront CDN, NGINX, Apache Tomcat, Git, Amazon Simple Notification Service (SNS), Docker Compose, Amazon Elastic Container Service (ECS), AWS IAM, Bitbucket, AWS ELB, AWS Command Line Interface (CLI), Google Kubernetes Engine (GKE), Google Analytics, PyCharm, Cron, Celery, Amazon EKS, Amazon Simple Queue Service (SQS), Amazon ElastiCache, Amazon Simple Email Service (SES), Helm, Pytest, Sentry, GitHub, AWS SDK, Azure Kubernetes Service (AKS), RabbitMQ, AWS CodeDeploy, Amazon Elastic Container Registry (ECR), Firebase Authentication
Languages
Python, JavaScript, Java, Groovy, SQL, HTML, CSS3, HTML5, Python 3, CSS, ECMAScript (ES6), TypeScript, Go, Solidity
Frameworks
Grails, Redux, Spring, Hibernate, Material UI, Express.js, Spring Boot, OAuth 2, Bootstrap, Django, gRPC, Locust, JSON Web Tokens (JWT), Flask, Gin-Gonic, NestJS, Next.js, Django REST Framework
Paradigms
REST, Socket Programming, Microservices, Test-driven Development (TDD), B2B, Unit Testing, API Architecture, Agile, Object-oriented Programming (OOP), Microservices Architecture, Back-end Architecture, Automation, Asynchronous Programming, Database Design, Object-relational Mapping (ORM), Testing, Role-based Access Control (RBAC), DevOps
Platforms
Docker, Kubernetes, Linux, Google Cloud Platform (GCP), Amazon EC2, Amazon Web Services (AWS), Firebase, Twilio, Azure, Heroku
Storage
MySQL, Amazon DynamoDB, Redis, Amazon S3 (AWS S3), MongoDB, Google Cloud, NoSQL, Databases, RDBMS, PostgreSQL, Relational Databases, JSON, Datadog, Redis Cache, Amazon Aurora, Elasticsearch, Cloud Firestore, SQL Server 2017
Other
FastAPI, Software Development, Amazon RDS, Web Development, Software Development Toolkits (SDK), APIs, Full-stack Development, Back-end Development, Amazon Route 53, Full-stack, Back-end, Payment APIs, Architecture, API Integration, SaaS, Fintech, Front-end, SDKs, AWS Auto Scaling, Software Architecture, CI/CD Pipelines, Cloud, AWS Certified Solution Architect, AWS Cloud Architecture, Web Applications, Front-end Development, User Experience (UX), MVC Frameworks, HTTP, User Interface (UI), Engineering, Webhooks, MERN Stack, Integration Testing, OAuth, Dashboards, Admin Panels, Third-party APIs, Back-end Performance, Payment Gateways, Solution Architecture, Payment Processing, Mobile Wallet, B2B Wallets, Technical Leadership, Distributed Systems, WebSockets, Containerization, Database Optimization, Leadership, Performance Optimization, RESTful Services, Scalability, Card Payments, Containers, PCI DSS, Task Scheduling, Orchestration, Async/Await, Software as a Service (SaaS), Credit Cards, AWS Secrets Manager, Caching, Code Review, GitHub Actions, System Architecture, Integration, Startups, Multithreading, Redis Streams, Polars, Observability, Infrastructure as Code (IaC), Pub/Sub, API Design, SQL Server, ECS, Fiber, Computer Science, Digital Payments, Online Payments, Azure Blob Storage
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