scalability

Hazelcast is a unified real-time data platform combining stream processing with a fast data store, allowing customers to act instantly on data-in-motion for real-time insights.

High performance reactive SQL client written in Java

Framework for Evolutionary Message-Driven Microservices on the JVM

Theodolite is a framework for benchmarking the horizontal and vertical scalability of cloud-native applications.

High-performance distributed rate limiter service with Redis backend. Supports token bucket and sliding window algorithms, dynamic configuration, and real-time metrics. Built for microservices architectures.

Oracle Coherence Community Edition

System design interview preparation for low-level design (LLD) and high-level design (HLD), with runnable dependency-free Java for every pattern, plus concurrency and timed machine-coding drills.

A curated collection of system design tutorials and hands-on projects covering scalable architecture, distributed systems, and real-world trade-offs. Hands-on system design tutorials for learning how to build scalable, reliable, and well-architected software systems.

Event sourcing for Java that scales horizontally: no global event log, no outbox, no central write bottleneck. DynamoDB/SNS/SQS reference implementation, Spring Boot starters

Scalable URL shortening system exploring hashing, storage design, and high-read workloads.

An extensible distributed system for reliable nearline data streaming at scale

TransactAlert — Asynchronous Fraud Alert Service | Java, Spring Boot, JMS ● Decoupled transaction ingestion from fraud analysis using a REST API and ActiveMQ Artemis message queue, so fraud checks run independently of the customer-facing request path instead of blocking it

A scalable Library Management System built using Spring Boot Microservices, Angular, API Gateway, JWT Authentication, RBAC, Azure Event Hub, Docker, Kubernetes, and Azure Cloud.

Spring Batch distributed partitioning using a shared database for coordination and failover

A multithreaded distributed server architecture in Java focused on concurrency, networking, scalability, and systems engineering.

A scalable Twitter-like social media feed system implementing hybrid fanout strategies to efficiently handle both regular users and celebrities with millions of followers. Features Spring Boot 3.x backend with PostgreSQL, Apache Cassandra, and Redis for optimized read/write performance across different user types.

Kafka load and stress testing

A scalable and fault-tolerant system leveraging Pub/Sub architecture on AWS EC2. Features include optimized message brokering, leader election, heartbeat protocols, and personalized weather alerts based on geographic and user preferences.

A comprehensive collection of System Design concepts, High-Level Design (HLD), Low-Level Design (LLD), distributed systems, scalability patterns, architecture diagrams, and real-world design case studies. This repository serves as a structured learning resource.

Real-time Communication Hub: STOMP WebSocket Chat, Redis Pub/Sub Clustering, and Connection Management