[INFO] Request GET /api/v1/user
[DEBUG] Cache hit for UID: 7281
[WARN] Latency threshold > 200ms
[INFO] Async job: reindexing...
[INFO] 200 OK (142ms)
[TRACE] JWT Validation successful
[INFO] Request POST /order/create
[DEBUG] Payload: {id: "TXN_99"}
[INFO] 201 Created
[INFO] Request GET /api/v1/user
[DEBUG] Cache hit for UID: 7281
[WARN] Latency threshold > 200ms
[INFO] Async job: reindexing...
_

SACHIN
KUMAR

Architecting high-concurrency systems & scalable microservices. Passionate about building robust enterprise backend solutions with Java & Spring.

View Projects → Initialize Contact
POOL_SIZE: 20/50
ACTIVE_CONN: 12
QUERY_AVG: 42ms
TX_COMMIT: SUCCESS
DEADLOCKS: 0
CPU_LOAD: 14.2%
HEAP_USAGE: 1.2GB/4GB
GARBAGE_COL: 12ms
POOL_SIZE: 21/50
ACTIVE_CONN: 14
CPU_LOAD: 15.8%
HEAP_USAGE: 1.3GB/4GB
Java 21Spring BootSpring AIRAGHibernateJPASpring SecurityREST APIsPostgreSQLSpring MVCEthereumSolidityMavenSpring AOPJUnitSpring Core Java 21Spring BootSpring AIRAGHibernateJPASpring SecurityREST APIsPostgreSQLSpring MVCEthereumSolidityMavenSpring AOPJUnitSpring Core

01. About_Me

Building systems that scale.

I'm Sachin Kumar, a dedicated Java backend engineer focused on architecting high-concurrency systems and enterprise-grade applications. My expertise spans the full Spring ecosystem — from REST API design to AI-powered backends using Spring AI and RAG pipelines.

Beyond the backend, I explore decentralised systems — my research on eVault demonstrates my interest in applying blockchain (Ethereum + Solidity) to solve real-world problems in legal record management.

I bring rigour to every layer: clean architecture, secure endpoints, testable code, and production-minded thinking.

Bangalore, India Backend Engineer Open to Opportunities 
const backendEngineer = {
  "name": "Sachin Kumar",
  "focus": "Backend Eng & AI Systems",
  "core_stack": [
    "Java 21",
    "Spring ",
    "Spring Boot",
    "PostgreSQL / JPA"
  ],
  "also_knows": [
    "Spring AI",
    "RAG",
    "Vector/Embeddings"
  ],
  "linkedin": "sachin-k-dev",
  // always learning...
};

02. System_Modules

Things I've shipped.

🛒
01 — Featured Project

AI-Powered E-Commerce Engine

A high-concurrency e-commerce backend with automated order processing and an intelligent RAG-based product search system. Integrates Spring AI with PgVector for semantic search, backed by a Spring Security layer and full CRUD REST APIs over PostgreSQL.

Java 21 Spring Boot Spring AI RAG PgVector PostgreSQL Hibernate Spring Security Docker Maven OpenAI
View Source Code
💼
02 — Backend Architecture

Job Application Portal

Service-oriented full-stack application with clean separation of concerns across Controller, Service, and Repository layers. Features secure authentication via Spring Security, JSP/Tomcat-powered views, and a PostgreSQL backend with full JUnit-tested endpoints.

Java 21 Spring Boot Spring MVC JSP Tomcat Maven Lombok JDBC PostgreSQL Spring Security JUnit / Mockito CSS
View Source Code
⚙️
03 — Infrastructure Module

Distributed Microservices Ecosystem

Architecting a resilient, distributed system utilizing Spring Cloud for centralized configuration, service discovery via Eureka, and fault tolerance with Resilience4j circuit breakers. Focuses on inter-service communication through OpenFeign and secure traffic routing via an API Gateway.

Java 21 Spring Boot Spring Cloud Eureka Config Server API Gateway Resilience4j OpenFeign Postman / cURL PostgreSQL
View Source Code

03. Research

Published work.

eVault for Legal Records

Designed and developed a secure, decentralised eVault system for legal record management leveraging Ethereum Smart Contracts and IPFS for immutable storage. The system uses cryptographic verification to ensure data integrity, MetaMask for user identity, and a Java SE backend — addressing the critical problem of tamper-proof, accessible legal document storage in the digital age.

Ethereum Solidity Smart Contracts Java SE Web3 Cryptography Blockchain DApps IPFS MetaMask Ganache Truffle

04. Tech_Stack

What I work with.

JAVA
BACKEND

05. Verified Expertise

Core Competencies.

⚙️
Microservices Architecture
Project-Based · Distributed Ecosystem
Implementing scalable backend services with centralized config, service discovery, and circuit breakers using Spring Cloud & Resilience4j.
🤖
Spring AI & RAG Systems
Project-Based · E-Commerce Platform
Hands-on implementation of Spring AI with OpenAI integration, PgVector for semantic search, and Retrieval-Augmented Generation pipelines.
⛓️
Blockchain & Smart Contracts
Research · eVault Publication
Original research in decentralised legal record management using Ethereum, Solidity, IPFS, and DApp development. Covers cryptographic verification.

Let's Connect.

Have a project, a role, or just want to talk? The connection is open.

Initialize Contact