Open-source alternatives to Advanced Java

NATS Server is a high-performance, lightweight messaging system designed for cloud-native applications, edge computing, and distributed microservices. It functions as a distributed publish-subscribe broker that routes messages using hierarchical, dot-separated subject strings, enabling decoupled communication between services without requiring centralized broker lookups. The system supports core messaging patterns including asynchronous publish-subscribe, request-reply, and load-balanced queue processing. The platform distinguishes itself through a decentralized architecture that eliminates t

This project is a reference implementation of microservices architectures using the Spring Cloud ecosystem. It provides a set of example services that demonstrate the construction of distributed systems through automated service discovery, dynamic routing, and shared configuration. The implementation covers core distributed patterns, including a service discovery system for tracking network components and an API gateway for orchestrating incoming traffic. It features a centralized configuration manager to propagate application settings across multiple instances and a distributed tracing syste

This project is a distributed systems design framework and architecture guide. It provides technical resources for designing, deploying, and coordinating independent network services. The framework establishes a structured methodology for migrating monolithic applications into decentralized services by separating frontend and backend concerns. It serves as a reference for event-driven architecture, focusing on maintaining data consistency across network boundaries using event sourcing and local transaction records. The project covers a broad range of capabilities including distributed servic

This project is a technical interview course and study guide focused on senior-level Java engineering. It provides a curriculum centered on system design, high-concurrency engineering, and the construction of distributed systems. The resources include a distributed database strategy guide and a microservices architecture reference. These materials cover specific design patterns for message queues, distributed systems, and the implementation of reliable asynchronous communication. The content covers broad capability areas including search engine architecture, distributed cache optimization, a

Hazelcast is a distributed data platform that combines an in-memory data grid with a stream processing engine to support real-time analytics and event-driven applications. It functions as a partitioned, distributed key-value store that replicates data across cluster nodes to provide low-latency access and high availability. The platform also serves as a distributed SQL query engine, allowing users to execute standard SQL statements against both in-memory datasets and external data sources. What distinguishes Hazelcast is its use of a distributed consensus subsystem to maintain strongly consis

This project is a comprehensive knowledge base and study resource designed for mastering technical interviews. It provides structured guides, roadmaps, and curricula focused on data structures, algorithms, system design, and frontend engineering to help candidates prepare for software engineering screenings. The repository distinguishes itself by offering a holistic approach to professional advancement. Beyond technical drills, it includes a career development handbook covering resume optimization, salary benchmarking, and strategic negotiation coaching. It also provides detailed methodologie

ShardingSphere is a distributed SQL database middleware that provides sharding, read-write splitting, and distributed transaction management for relational databases. It functions as a layer that intercepts SQL queries to distribute data across multiple physical database instances for horizontal scaling. The project is distinguished by its ability to operate as either a standalone transparent database proxy or via direct integration as a JDBC driver. It features a SQL dialect translator that parses queries into abstract syntax trees to convert syntax between different database engines, enabli

brpc is a high-performance C++ RPC framework and network programming library designed for building distributed systems. It functions as a multi-protocol RPC server capable of hosting and detecting multiple communication protocols, including gRPC, Thrift, HTTP, Redis, and Memcached, on a single TCP port. The project distinguishes itself through high-throughput data transport and memory efficiency, utilizing RDMA-based transport to bypass the kernel TCP stack and zero-copy memory management to eliminate data duplication. It also implements the Raft algorithm for consensus-based state replicatio

VictoriaMetrics is a high-performance, scalable time series database and observability platform designed for long-term storage and analysis of metric, log, and trace data. It functions as a unified backend for monitoring ecosystems, offering full compatibility with industry-standard protocols and query languages. The system is built to handle massive data volumes through a distributed architecture that supports horizontal scaling and efficient data lifecycle management. The platform distinguishes itself through a storage engine that utilizes consistent hashing for data sharding and log-struct

This project is a reference implementation of a distributed system built using Spring Cloud Alibaba, Spring Boot, and JDK 17. It serves as a comprehensive model for implementing a microservices architecture. The system integrates a wide range of distributed patterns, including global transaction coordination for data consistency, OAuth2 and JWT for identity management, and Kubernetes-based container orchestration. It features a dedicated observability stack for distributed request tracing, log aggregation, and service health monitoring. The implementation covers several functional domains, i

SpringBlade is a development framework and platform designed for building multi-tenant SaaS applications. It provides a comprehensive scaffold for both Spring Cloud microservices and monolithic Spring Boot architectures, enabling the rapid construction of enterprise-grade software. The platform distinguishes itself through integrated LLM orchestration and industrial IoT management. It features an LLM orchestration platform that combines large language models with knowledge bases and visual AI agent workflows, alongside an IoT hub for device connectivity, state synchronization, and edge flow o

This project is a comprehensive educational resource and study guide focused on distributed systems architecture and backend infrastructure design. It provides a structured curriculum for mastering the principles of scalability, reliability, and performance required to design complex software systems. The repository distinguishes itself by offering a methodical approach to technical interview preparation, incorporating design patterns, architectural trade-offs, and spaced repetition tools to help users retain complex concepts. It emphasizes constraint-driven analysis, teaching users how to ev

This project is a comprehensive educational resource focused on the principles, patterns, and trade-offs required to design scalable, reliable, and high-performance distributed systems. It provides a structured curriculum that covers the fundamental architectural strategies necessary for building modern software infrastructure, ranging from high-level system decomposition to low-level networking and data management. The repository distinguishes itself by offering deep dives into complex architectural patterns, such as microservices-based decomposition, event-driven communication, and command-

Olric is a distributed data grid and in-memory key-value store that partitions and replicates data across a cluster of servers. It serves as a shared memory system for managing distributed maps, performing atomic operations, and acting as an in-memory data cache. The system provides a distributed locking mechanism for concurrency control and a pub-sub messaging system that broadcasts and routes messages over named channels across the cluster. The platform covers wide-ranging capabilities including cluster management and orchestration, data replication with configurable quorums, and automated

Hystrix is a latency and fault tolerance library designed to prevent cascading failures in distributed systems. It functions as a circuit breaker implementation that monitors failure thresholds and opens circuits to isolate remote calls when downstream services degrade. The project distinguishes itself by providing multiple isolation mechanisms, utilizing dedicated thread pools and semaphores to ensure that latency in one dependency does not saturate the entire system. It also features a request collapsing and batching engine that groups concurrent calls into single executions to reduce the t

This is a remote procedure call framework built on Netty for asynchronous communication between distributed services. It provides the infrastructure necessary to execute remote procedure calls across a network, allowing clients and servers to interact without blocking. The framework utilizes Zookeeper for service registration and dynamic discovery, ensuring that service providers can be located automatically at runtime. It includes a service versioning manager to organize and track different iterations of service interfaces, enabling side-by-side deployments of multiple versions. The system

This project is a microservices reference architecture and polyglot suite designed as a containerized application demo. It provides a deployable environment that functions as a container orchestration testbed to evaluate the performance and stability of various orchestration tools. The suite implements a polyglot architecture where independent services are written in different languages, each managing its own private database. It utilizes an event-driven distributed system model, employing asynchronous messaging and decoupled data stores to coordinate workflows across separate business domain

phpredis is a C-based native extension that bridges PHP applications with Redis servers for high-performance data storage and retrieval. It serves as an interface for manipulating strings, hashes, lists, sets, and sorted sets while providing a direct path for executing Redis commands and server-side scripts. The extension provides comprehensive support for distributed environments and high availability. It interfaces with Redis Cluster to distribute data across multiple nodes using hash slots and manages Redis Sentinel for service discovery and automatic failover. It also enables shared state

InternetArchitect is an educational collection of documents and source code designed as a high concurrency architecture course. It serves as a distributed systems implementation guide, providing technical patterns and practical examples for designing scalable internet architectures that maintain stability under heavy traffic loads. The project focuses on high-performance database optimization and microservices design patterns. It covers strategies for reducing latency and increasing throughput via database sharding and proxy layers, as well as coordinating global state across distributed clus

m3 is a distributed time series database designed for high-resolution metrics and high-cardinality data management. It functions as a scalable storage system and a multi-cluster query engine, providing a distributed metrics aggregator capable of downsampling and summarizing data before it is committed to storage. The project distinguishes itself through a coordinated cluster model using etcd for node membership and shard placement. It supports multiple ingestion protocols, including the Prometheus remote write protocol, InfluxDB line protocol, and Graphite Carbon plaintext protocol, and provi

Ribbon is a client-side load balancer and RPC communication library designed for inter-process communication. It functions as a fault-tolerant network proxy that distributes outgoing network requests across a pool of available server instances to prevent node overload. The project integrates as a service discovery client, maintaining synchronized lists of available server instances by connecting with cloud environment discovery tools. This allows it to manage request retries and failover behavior when remote servers become unresponsive. The library supports a protocol-agnostic transport laye

SpringCloud-Learning is an educational project that demonstrates how to build microservices using Spring Cloud, covering the core patterns of service discovery, centralized configuration management, and API gateway routing. The project provides hands-on examples for registering and discovering microservice instances with Nacos, Eureka, or Consul, and for routing external API requests through Spring Cloud Gateway with support for filters and load balancing. The tutorials explore service resilience through circuit breakers and rate limiting with Sentinel and Hystrix, including custom fallback l

Spring Cloud Alibaba is a suite of libraries designed to connect distributed Java applications to Alibaba cloud middleware and infrastructure services. It provides a comprehensive set of tools for messaging, configuration, task scheduling, transaction coordination, and service discovery. The project implements distributed infrastructure capabilities including a transaction coordinator for maintaining data consistency across multiple services and a configuration manager for storing external settings in a centralized cloud repository with automatic updates. It includes a distributed job schedul

Godis is a Redis-compatible in-memory database and distributed key-value store. It functions as a replicated data store and distributed message broker, implementing the Redis protocol to manage complex data structures in memory. The system provides a geospatial indexing engine for proximity-based queries and distance calculations. It ensures high availability and data durability through master-slave replication and write-ahead logging. The project covers a wide range of capabilities including the management of strings, hash maps, lists, and sorted sets. It supports distributed data clusterin

This project is an integration framework that bootstraps Apache Dubbo remote procedure call services within Spring Boot applications. It serves as a microservice communication framework that enables the implementation of RPC services, service discovery, and distributed governance through automated configuration. The project distinguishes itself by providing a cross-language RPC bridge, allowing services written in different languages to communicate via standards such as gRPC and Protobuf. It further enables the exposure of backend microservices as REST endpoints using the Triple protocol for

rpcx is a high-performance remote procedure call framework for building scalable microservices in Go. It functions as a binary protocol RPC system and a service mesh, providing the necessary infrastructure for low-latency inter-service communication and distributed cloud environments. The project features a cross-language service gateway that provides an HTTP entry point, allowing clients written in any programming language to invoke Go remote services via protocol translation. It also includes a specialized RPC traffic analyzer for capturing and analyzing binary packets to debug network comm

Finagle is a distributed service mesh and fault-tolerant remote procedure call framework. It provides a protocol-agnostic network library that implements a consistent interface for different network standards, including HTTP and Thrift. The project distinguishes itself by integrating a fault tolerance library that prevents cascading failures through circuit breaking and timeout management. It also implements a distributed tracing system to track requests across network boundaries and visualize call graphs. The framework covers several core capability areas, including dynamic service discover