Distributed Systems
Architecting resilient distributed systems and scalable microservice patterns for enterprise workloads.
Available for backend engineering roles · India
Hi, I'm Rajeev Nayan
Java Backend Engineer & System Architect
Java Backend Engineer
Build scalable, secure, high-performance backend systems using Java, Spring Boot, Microservices, REST APIs, SQL, Docker, and Cloud technologies.
- 69
- Public repos
- 15+
- REST endpoints shipped
- 30%
- API latency reduced
SystemController.java
LIVE
CPU: 12%
Heap: 42MB
12ms
JavaSpring BootPostgreSQLRedisDockerJWTHibernateAWS
Engineering Philosophy
Backend engineering, done deliberately
I am an MCA graduate and Java Backend Developer specializing in the Java & Spring Boot ecosystem. I focus on building production-grade microservices, secure REST APIs, and AI-powered RAG systems. My engineering approach is built on three pillars: Clean Code, Reliability, and Performance.
My work spans enterprise domains — hospital management, fintech expense tracking, ticket booking and distributed order systems — where correctness, authentication and query performance matter more than surface polish. I ship with Docker, PostgreSQL, Redis and CI pipelines wired in from day one.
Education
Master of Computer Applications (MCA)
Dr. A.P.J. Abdul Kalam Technical University
2022 — 2024 · Uttar Pradesh, India
API Engineering
Designing high-throughput APIs and robust server-side logic using modern Java and Spring ecosystems.
Data Engineering
Engineering efficient data flows and high-performance storage solutions using PostgreSQL and Redis.
Security by Design
Implementing secure-by-design principles and fault-tolerant patterns for mission-critical apps.
Tech Stack
The tools behind the services
A multi-layered ecosystem optimized for high throughput, maintainable microservices, and secure distributed data flows.
Languages
4- Java
- SQL
- JavaScript
- TypeScript
Backend
8- Spring Boot
- Spring MVC
- Spring Security
- Spring Data JPA
- Hibernate
- REST APIs
- JWT
- OAuth2
Architecture
6- Microservices
- MVC
- Clean Architecture
- Layered Architecture
- Repository Pattern
- SOLID Principles
Databases
5- MySQL
- PostgreSQL
- Oracle
- MongoDB
- Redis
DevOps
5- Docker
- Git
- GitHub Actions
- Maven
- Gradle
Cloud
4- AWS
- Render
- Railway
- Vercel
Tools
5- IntelliJ IDEA
- VS Code
- Postman
- Swagger/OpenAPI
- Bruno
Professional Track
Career Timeline
Java Developer Intern
Jspider Private Limited
Bengaluru, India Feb 2025 — Aug 2025
Developed production-grade Spring Boot microservices, secure REST APIs, and automated deployment pipelines.
- Launched and deployed 4 Spring Boot microservices with Docker Compose; reduced API latency by 30% through Redis caching and Hibernate query optimization.
- Engineered 15+ secure REST endpoints using Spring Security, JWT, and OAuth2; sustained 5,000+ daily requests at 99.9% uptime across staging and production.
- Automated CI/CD with Jenkins and GitHub Actions, integrating SonarQube quality gates, cutting release cycle time by 25%.
- Maintained 80%+ unit test coverage using JUnit 5 and Mockito in a 6-member Agile Scrum team on 2-week sprints.
Open Source Backend Projects
Independent / GitHub
Remote 2024 — Present
Shipping 69 public repositories, focused on Spring Boot services, Spring AI RAG pipelines and DSA practice in Java.
- Authored Food Fiesta — a Spring Boot ordering platform with Spring MVC, Thymeleaf, multithreading and RESTful APIs (19 stars, 12 forks).
- Built Spring AI RAG systems (pdf-rag-spring-ai, rag-chatbot-springboot) using pgvector, embeddings and semantic search over uploaded documents.
- Delivered full-stack enterprise systems with Spring Boot 3 + React 19, JWT security, PostgreSQL and Redis.
- Maintains Java + SQL DSA solution sets across LeetCode, GeeksforGeeks and NeetCode.
Coding & Problem Solving
Consistent practice in Data Structures, Algorithms and problem solving.
Source: Fresh
Last synced: 9:48:02 PM1302+Problems Solved
3Coding Platforms
ActiveProblem Solving
Featured Work
Architectural Deep Dives
Live metrics pulled from GitHub on every render — stars, forks, languages and last activity are real.
Sort
Web Platform
IntermediateFood Fiesta
21
12
Spring Boot web application for online food ordering — browse menus, manage a cart and place orders, with an admin surface for menu and order management.
The Challenge
Restaurant ordering flows break under concurrent traffic — carts drift out of sync and admins lose visibility of incoming orders.
Engineering Fix
A layered Spring MVC application where ordering, menu and admin concerns are isolated behind services, with multithreaded order processing so concurrent placements never block each other.
System Design
Request flow
Client→REST Controller→Service Layer→JPA Repository→Database
Service Execution Path
Thymeleaf / REST client
Controller
Order service (threaded)
Spring Data JPA
SQL database
Technical Trade-offs
Spring MVC + Thymeleaf•Server-rendered flows keep cart state authoritative on the server.
Multithreading•Concurrent order handling without serialising the checkout path.
Spring Data JPA•Repository abstraction over the order and menu aggregates.
Java 8+Spring BootSpring MVCThymeleafSpring Data JPAREST APIsMultithreading
JavaSync: Aug 26
Enterprise Systems
ExpertEnterprise Expense Tracker
4
3
Full-stack enterprise financial dashboard built on Spring Boot 3 and React 19, with JWT security, PostgreSQL persistence and Redis caching.
The Challenge
Finance dashboards aggregate the same expensive queries on every page load, and expense data must stay scoped per role.
Engineering Fix
A stateless Spring Boot 3 API secured by a JWT filter chain, with PostgreSQL as system of record and Redis caching the dashboard aggregates.
System Design
Request flow
Client→Security Filter→REST Controller→Service Layer→Redis Cache→PostgreSQL
Service Execution Path
React 19 SPA
JWT filter
REST controller
Service layer
Redis cache
PostgreSQL
Technical Trade-offs
JWT + Spring Security•Stateless auth that scales horizontally with no session store.
Redis•Read-through cache removes repeated aggregate scans on the dashboard.
PostgreSQL•Indexed reporting queries over transactional expense data.
Java 21/25Spring Boot 3Spring SecurityJWTPostgreSQLRedisDockerReact 19
JavaSync: Jun 26
Distributed Systems
ExpertBookMyShow Clone
3
2
High-performance movie ticket booking system built with Java, Spring Boot and React — premium dark-mode UI over a transactional seat-booking core.
The Challenge
Seat inventory is a classic race condition — two users must never book the same seat.
Engineering Fix
Transactional seat locking inside the booking service, so reservation and payment confirmation happen inside one atomic boundary.
System Design
Request flow
Client→REST Controller→Service Layer→PostgreSQL
Service Execution Path
React client
Booking controller
Transactional seat lock
Booking service
PostgreSQL
Technical Trade-offs
Transactional locking•Prevents double booking under concurrent seat selection.
PostgreSQL•ACID guarantees on the shows, seats and bookings tables.
REST + React•Real-time seat state rendered from a single API contract.
JavaSpring BootREST APIPostgreSQLReact
JavaSync: Jul 26
Enterprise Systems
AdvancedHospital Management System
1
0
Comprehensive, secure backend for hospital operations built with Spring Boot 3.x — users (patients, doctors, nurses, admins), appointments and medical records.
The Challenge
Hospital data is inherently multi-tenant by role — patients, doctors, nurses and admins must never see each other's records.
Engineering Fix
A role-partitioned domain model where every endpoint is authorised through Spring Security, with appointments and medical records isolated as independent service modules.
System Design
Request flow
Client→Security Filter→REST Controller→Service Layer→PostgreSQL
Service Execution Path
Client
Security filter
Role-scoped controller
Domain service
JPA repository
PostgreSQL
Technical Trade-offs
Spring Security•Authorisation enforced at the endpoint, not in UI code.
Docker Compose•Reproducible environment parity across dev and staging.
PostgreSQL•Relational integrity for appointments and clinical records.
Java 25Spring Boot 3Spring SecurityPostgreSQLDockerDocker Compose
JavaSync: May 26
AI / RAG
ExpertPDF RAG with Spring AI
0
0
Retrieval-Augmented Generation application built with Spring AI — document ingestion, vector search and AI-powered question answering over PDFs.
The Challenge
LLM answers over private documents hallucinate without grounded retrieval.
Engineering Fix
An ingestion pipeline that chunks and embeds PDFs into pgvector, plus a retriever that grounds every model response in the retrieved passages.
System Design
Request flow
Client→REST Controller→Service Layer→pgvector
Service Execution Path
PDF upload
Chunk + embed
pgvector store
Semantic retrieval
Spring AI + LLM
Answer
Technical Trade-offs
Spring AI•First-class embedding and retrieval abstractions inside the Spring stack.
pgvector•Vector search next to relational data — one database to operate.
Chunked embeddings•Keeps retrieval precise on long documents.
JavaSpring BootSpring AIpgvectorEmbeddingsVector SearchLLM
JavaSync: Jun 26
Microservices
IntermediateURL Shortener Service
0
0
Spring Boot service that generates unique short links for long URLs, exposing REST APIs for creation, retrieval and redirection.
The Challenge
Redirects are a hot read path — code generation must be collision-safe while resolution stays sub-millisecond.
Engineering Fix
A stateless REST service with a collision-safe short-code generator and a dedicated redirect controller kept off the write path.
System Design
Request flow
Client→REST Controller→Service Layer→JPA Repository→SQL
Service Execution Path
Client
Create endpoint
Code generator
JPA persistence
Redirect controller
Technical Trade-offs
Stateless service•Horizontally scalable behind any load balancer.
Spring Data JPA•Simple, indexed lookups on the short-code column.
Dedicated redirect path•Read path isolated from creation logic.
JavaSpring BootSpring Data JPAREST APIsSQL
JavaSync: May 26
System Design & Expertise
Where the hard problems live
Five areas that decide whether a backend holds up in production.
REST API Development
Contract-first endpoints that stay predictable under load.
01CRUD APIs
02Pagination
03Filtering
04Validation
05Exception Handling
06API Versioning
System design principles
The defaults I reach for when a service has to grow past a single instance.
01
Scalable Architecture
Stateless services, horizontal scaling and clear bounded contexts per domain.
02
API Gateway
Single entry point for routing, auth propagation and cross-cutting concerns.
03
Caching
Read-through Redis layers on aggregate-heavy endpoints, with explicit invalidation.
04
Database Optimization
Index design, query plans and connection pooling over premature sharding.
05
Distributed Systems
Idempotency, retries and failure isolation between service boundaries.
Architectural Playground
High-Performance Backend Sandbox
Interactive visualization of a production-grade Java microservice stack. Click components to inspect internal state or trigger a request flow.
Cluster: us-east-1
Spring
Microservice
Redis
PostgreSQL
System Metrics
P99 Latency12.0ms
Throughput450 rps
CPU Load18.0%
Heap Usage240MB
Select a component to view internal architectural details.
AI / RAG Integration
How Rajeev AI Works
An interactive look at the Retrieval-Augmented Generation pipeline powering the AI assistant on this site.
User Query
The natural language request enters the system.
Vector Embedding
Text is converted into high-dimensional numerical vectors using an embedding model.
Semantic Retrieval
The vector is compared against a pgvector store to find relevant knowledge chunks.
Augmented Generation
Retrieved context + user query are passed to the LLM to generate a grounded response.
Live Pipeline Trace
Active
[QUERY]What are Rajeev's core Java skills?
Try a Query
This simulation demonstrates how the backend uses pgvector for vector storage and Spring AI to orchestrate the retrieval flow, ensuring the AI assistant doesn't hallucinate and stays grounded in Rajeev's actual professional data.
Open Source Contributions
Live activity from @imrajeevnayan
Fetched server-side from the GitHub API — nothing here is hardcoded.
0
Public repositories
0
Stars earned
0
Followers
0
Recent Contributions
Language usage
- Java28 repos · 43%
- HTML14 repos · 22%
- JavaScript9 repos · 14%
- TypeScript9 repos · 14%
- CSS4 repos · 6%
- PHP1 repos · 2%
Recent activity
view all →- imrajeevnayanJavaScript · 2026-08-10
- leetcode-solutionJava · 2026-08-10
- a2z-dsa-sheetJava · 2026-08-10
- rajeevnayanTypeScript · 2026-08-10
- neetcode-submissionsJava · 2026-08-08
- Food-FiestaJava · 2026-08-07
Top repositories
- Food-Fiesta★ 21 · ⑂ 12
- hospital-management-springboot★ 4 · ⑂ 2
- Enterprise-Expense-Tracker★ 4 · ⑂ 3
- BookMyShow★ 3 · ⑂ 2
- Hospital-Management-System★ 1 · ⑂ 0
Contribution graph
0
Last 12 months
0
Current streak
0
Best day
Performance Metrics
Navigation Load—ms
DOM Complexity— nodes
* Real-time client-side telemetry captured during current session initialization.
Optimization Status
Mobile OptimizationActive
Motion ThrottlingHardware Accelerated
Automatic adjustment based on device capabilities and system preferences is enabled.
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