Kundan K.Private profile: Upwork shows its earnings only to signed-in members, so we check it every few weeks, not daily. MRR here is a rough estimate (Upwork's six-month earnings ÷ months active). Last read Nov 5, 2026.

Senior Backend-heavy Full Stack Engineer - 14+ years shipping Java/Spring Boot, Golang systems, now building Agentic AI, RAG pipelines, and MCP servers on top of them. Current work: a HIPAA-aligned medspa CRM where I own backend and frontend, plus a LightRAG-powered engine that reads inbound patient email/SMS and drafts context-aware replies from the clinic's own knowledge base. ━━━ HEALTHCARE / HEALTHTECH ━━━ - MedSpa CRM platform — patient records, appointments, campaigns, billing. Spring Boot microservices + Angular/React (TypeScript) frontend. - AI patient communication — LightRAG retrieval over clinic documents, treatment menus and conversation history; automated email + SMS replies with human-in-the-loop review. - FHIR R4 integration and EHR interoperability — Patient, Practitioner, Appointment, Encounter, Observation resources; HL7 mapping. - PHI encryption in transit and at rest, audit logging, HIPAA / GDPR / PCI DSS alignment, OWASP hardening. ━━━ AGENTIC AI & RAG (open-source first) ━━━ - LightRAG, LangChain4j, OpenHands — multiple RAG and multimodal features in production. - MCP server development in TypeScript, deployed on Railway. Custom agents and MCP connectors configured in Claude workspaces. - Vector databases — Pinecone, ChromaDB. Embeddings, chunking strategy, memory graphs, retrieval tuning. - LLM platforms — OpenAI, Anthropic, Gemini, DeepSeek. Advanced prompt engineering and AI memory/context management. - Workflow automation — n8n and Make wired into backend services and agents. ━━━ FINTECH & TAX COMPLIANCE ━━━ - EU VAT filing platform — Spring Boot backend pulling master and transactional data from SAP via CDS views, feeding a country-specific calculation engine that produces returns in each tax authority's required submission format. - Built the rules layer so per-country VAT logic, rates and edge cases stay configurable rather than hardcoded — new jurisdictions onboard without a rewrite. - Trading systems experience with FIX protocol and QuickFIX-J. ━━━ ENTERPRISE / SAP REAL-TIME INTEGRATION ━━━ - Designed and built SAP-to-application integration over Solace PubSub+ — SAP publishes business events to queues, Java consumers process, transform and persist them, so in-house applications run on live data instead of nightly batches. - Guaranteed delivery, ordering, replay and error/DLQ handling on the consumer side. Solace Certified Solutions Consultant. - Broader integration work: SAP Master Data, Salesforce, Amdocs CRM, HubSpot, Zoho CRM, Weclapp ERP, QuickBooks, Xero, Stripe, PayPal, Decoda Health. MuleSoft solutions built and deployed via Anypoint Studio and CloudHub. ━━━ EV CHARGING (Lade GmbH) ━━━ - Charge process management and charger device management backend — session lifecycle, device state, telemetry, and operational dashboards. - Weclapp ERP integration for billing and business data flow between charging operations and back office. ━━━ RECRUITMENT / TALENT PLATFORMS ━━━ - Talent tracking system and recruitment portal — backend powering separate Talent and Recruiter web portals plus the mobile apps, on a shared API layer. - Candidate pipeline and stage management, matching and search, notifications, role-based access across candidate, recruiter and admin. ━━━ BACKEND & ARCHITECTURE ━━━ - Java 8–21, Spring Boot, microservices, REST / SOAP / gRPC / GraphQL. - Event-Driven Architecture — Solace PubSub+, Kafka, AxonIQ, KubeMQ, Event Sourcing, CQRS. SOA with MuleSoft and Apache Camel. - Legacy modernization — legacy Java to Spring Boot, SOAP to REST, javax to jakarta migration (servlets, websockets), technical debt removal. - Design patterns, DDD, TDD, SOLID, Circuit Breaker. ━━━ CLOUD, DEVOPS & DATA ━━━ - AWS (EC2, ECS, RDS, S3, Lambda, CDK, Cognito, CloudWatch), Azure (APIM, Pipelines, Azure SQL), GCP (App Engine, BigQuery, Firebase), Railway, Heroku, DigitalOcean. - Docker, Kubernetes, GitLab CI/CD, GitHub Actions, Bitbucket. - PostgreSQL, MySQL, MongoDB, Elasticsearch, SAP HANA. ━━━ FRONTEND & DESKTOP ━━━ - Angular, React, TypeScript, JSP, JSF. - Java Swing and JavaFX for industrial automation dashboards, including HID and industrial hardware device integration. ━━━ CERTIFICATIONS ━━━ Oracle Certified Java Professional · Solace Certified Solutions Consultant M.C.A. (Computer Applications) · B.Tech (Information Technology) Also: Kotlin, Groovy, Go, Python, C++, Salesforce Apex, Android (Java/Kotlin). Use Claude Code and Codex to ship code faster, Self motivated and work without supervision