K. Vedant MahajanSenior Software Engineer & Tech Lead | Node.js · Java · PostgreSQL · Applied AI
Profile

Senior Backend Engineer with 11+ years of experience, including hands-on Tech Lead scope at both Khatabook and Toppr/​Byju's. Designed rule engines, event-driven integrations, and geospatial services processing 8.5 million daily SQS transactions in Node.js, Java 17, and PostgreSQL. Led a team of 3–5 engineers as Principal Engineer at Toppr/​Byju's, scaling India's #1-ranked Q&A product to 35M MAU. Actively building Applied AI and Generative AI engineering depth — hands-on with RAG pipelines, semantic embeddings, vector similarity search, and LLM API integration

Professional Experience
SDE 3 (Backend)
  • •Architected and delivered an automated IVR calling worker (NestJS) over a multi-tenant SQS-based notification pipeline processing 8.5M daily messages — implementing per-tenant Exotel rate limiting (Redis token bucket), transactional bulk assignment, and async webhook-driven status tracking across COMPLETED /​ NO_ANSWER /​ FAILED states — directly replacing a manual CS calling operation and enabling the company to downsize and relocate the CS function from Bangalore to Jaipur, significantly reducing operational overhead
  • •Implemented PostGIS distance-based sorting: Enabled real-time distance calculation between user GPS and lead locations. Devised priority-based fallback (selfie location → landmark) and spatial index optimization (ST_Distance), preserving existing query structure while adding spatial operations without breaking backward compatibility.
    • Apr 2025 – May 2026Bangalore, India
  • •Optimized lead search performance: Accelerated query performance by optimizing complex filter handling and join resolution. Hardened the dynamic query builder to handle edge cases (hub-to-pincode conversion) while maintaining security through input sanitization.
  • •Contributed to a Java 17 / Spring Boot digital lending microservice (Khatabook Loans) — extended the configurable loan journey engine by implementing a new step processor following the StepProcessorInterface contract (preprocess → validate → update lifecycle). Worked across a codebase handling full loan lifecycle: origination, multi-NBFC lender routing, NACH repayments, and settlement reconciliation. Stack: Java 17, Spring Boot, Spring Data JPA, PostgreSQL, Redis, Resilience4j, AWS SQS/S3
    • SDE-2 ( Full stack )
  • •Enhanced multi-constraint lead allocation engine: Steered a rule-based allocation system balancing language matching, workload distribution, and sticky allocation. Refined dynamic SQL query generation and allocation configs, overcoming single-worker architecture limitations to ensure strong consistency
  • •Streamlined Concurrent Bulk Operations: Executed bulk assignment processing with controlled concurrency and per-assignment transaction isolation, with comprehensive error handling, audit logging, and CSV-based tracking
    • Dec 2023 – Mar 2025Bangalore, India
  • •Built Underwriting (UW) Task Flow from scratch: Designed and implemented a rule-based task creation system and engineered a task allocation worker with priority-based sorting. Codified 7+ business rules using a rules engine pattern where rules execute independently, and architected a multi-step verification workflow using a Strategy pattern for task types (UW, Fraud) to enable extensible workflows.
  • •Optimized lead management system serving 2 client applications (mobile app, web dashboard) with integration to upstream loan origination and downstream notification services, processing thousands of leads daily
    • Quillbot⁠, FullStack Engineer (Platform Team)

    Contributed to the end-to-end feature delivery for an enterprise-wide CMS product. Improved system stability and application reliability by driving a complete architectural overhaul of frontend state management flows

    Apr 2023 – Aug 2023Remote
    Principal Engineer
  • •Led engineering of Toppr's Q&A product to India's #1 educational app ranking (SimilarWeb, 35M MAU) — outperforming Byju's own product, directly contributing to Toppr's acquisition. Owned full technical roadmap across performance, stability, and feature delivery for a team of 3–5 engineers.
  • •Architected AskAnExpert as modular npm packages in a monorepo — converting a monolithic Q&A product into a plug-and-play integration layer adopted across Toppr Ask, Byju's QnA, and internal products, driving a high-revenue monetisation stream.
    • Jul 2022 – Mar 2023Remote, India
    Tech Lead
  • •Led a team of 3–4 engineers resolving critical memory overflow issues causing 5xx errors on a Next.js platform serving lakhs of content pages across text, media, and video formats. Drove continuous page speed and bundle size optimisation pre-deployment via load testing (npm loadtest) and pm2 stage monitoring.
  • •Built CI/​CD pipelines with automated linting gates, failing builds on threshold breaches, and Bitbucket webhook integrations with Slack and email for pre-deployment quality enforcement. Used Screaming Frog crawler for post-production page crawl health monitoring.
    • Sep 2020 – Jun 2022
  • •Mentored 3–4 junior engineers including participation in performance review cycles.
    • Senior Software Engineer
  • •Built the foundational frontend infrastructure at Turtlemint — server-driven configurable checkout flows, the core component library @turtlemint/​mint-ui ( a monorepo), and @turtlemint/​redux-analytics for automating event tracking through Redux actions — enabling consistent, scalable development across vertical teams.
    • Jul 2019 – May 2020Mumbai, India
    Software Engineer
  • •Contributed to core platform optimisation as part of the platform team — iteratively built a React.js boilerplate benchmarked against the popular react-boilerplate open source standard, achieving superior performance and smaller bundle size through measured, incremental library and tooling additions
    • Dec 2018 – Jun 2019Mumbai, India
    Software Engineer | Freelance → Alfa KPO → Justdial → NSE IT → Cogoport

    Progressed through engineering roles across freelance web development, React, Angular, Ionic, and Node.js.

    Built client websites, email marketing portals, hybrid mobile apps (Firebase push notifications), admin

    Dec 2013 – Jul 2018Mumbai, India

    dashboards, and web portals.

    Projects
    AI Engineering Projects | Independent (2026–present)
  • •Production RAG Pipeline — Built end-to-end Retrieval Augmented Generation system in Node.js/​NestJS: semantic chunking, pgvector similarity search (cosine), augmented prompt construction with XML structure, streaming SSE endpoint with citation parsing, Zod schema validation with retry logic, and confidence threshold gating. Prevents hallucination by constraining LLM to retrieved context only.
  • •Multi-tool LangGraph Agent — Built a stateful ReAct agent using LangGraph.js with multiple tool definitions, PostgreSQL checkpointing for state persistence, human-in-the-loop approval node for irreversible actions, and conditional routing between tool execution and final answer generation.
    • Jan 2026 – Present
  • •Semantic Search Service — NestJS service using all-MiniLM-L6-v2 embeddings and pgvector. Model loaded once at onModuleInit to prevent thundering herd on restart. SQL-level threshold filtering to use pgvector index correctly. Returns similarity confidence score alongside results.

    • Independent Project — Real Estate Tech Platform | Sep 2023 | Bangalore

    Built a real estate discovery platform integrating RERA data pipelines for automated fact-checking, a multi-signal Trust Score algorithm, and an AI-powered preference matching layer using semantic embeddings and vector similarity search. Applied RAG-style retrieval architecture hands-on

    Skills
    Backend Ecosystem — Node.js, NestJS, Express.js, PostgreSQL, PostGIS, Redis, SQL, Kafka, Amazon SQS, Java, Spring Boot, Spring Data JPA, Resilience4j, AWS S3, Kubernetes
    Languages — JavaScript/Typescript, Java, Python, C++, PHP
    Frontend Ecosystem — React.js, Next.js, Redux, React Query, HTML/CSS, SCSS, TailwindCSS, Webpack
    Observability — Coralogix, Grafana, Lens, AWS cloudwatch, Datadog, Sentry, New Relic
    System Design & CS Fundamentals — High-Level Design (HLD), Low-Level Design (LLD), Data Structures & Algorithms, Microservices Architecture, Event-Driven Architecture, API Design Patterns, Database Query optimisations, Caching Strategies, Message Queue Patterns (SQS, Kafka), WebSockets, Web Security (OWASP), Web Performance Optimisation
    Applied AI & Generative AI Engineering: — RAG Pipeline Design, Semantic Embeddings, Vector Similarity Search (pgvector), LLM API Integration (OpenAI, Anthropic), Prompt Engineering, LangChain, Agentic AI Workflows, Generative AI Application Architecture, AI-Assisted Development (Cursor)
    Leadership & Collaboration — Technical Mentorship, Team Leadership (3–5 engineers), Code Review, Technical Roadmapping, Architecture Decision Records (ADRs), Cross-functional Collaboration, Agile/Scrum Delivery
    Professional Development
    Artificial Intelligence & Machine Learning Program, Scaler Academy
    Feb 2026 – PresentIndia
    Jan 2020 – Aug 2020Remote, India
    Education
    B.Tech - Major in Computer science engineering, I.K. Gujral Punjab Technical University⁠
    2009 – 2013Gurdaspur, India
    Awards

    AIR 119, Global 1709. Kickstarted with a brute-force solution and iterated to

    competitive ranking with a backtracking approach

    Feb 2020