Open-source alternatives to Paho.mqtt.java

This library is an Arduino-compatible client for the messaging protocol designed for resource-constrained embedded systems. It provides a messaging interface that enables microcontrollers to establish persistent connections with brokers to exchange data and control signals. The library distinguishes itself through a focus on predictable resource usage, utilizing manual memory buffer management and a state-machine approach to handle connection persistence and automatic reconnections. It operates on a stream-oriented network abstraction, allowing it to interface with various hardware transport

libwebsockets is an event-driven networking framework written in C. It provides a suite of tools for implementing HTTP servers and clients, WebSocket bidirectional communication, MQTT client messaging, and TLS-enabled socket encryption. The project distinguishes itself through a non-blocking event-loop architecture capable of scaling to high connection volumes by distributing network sessions across multiple service threads. It uses a protocol-based callback system and a pluggable event loop integration that allows the networking core to synchronize with external system event libraries. The

This project is the official documentation site and communication standard portal for the MQTT messaging protocol. It serves as a central hub for technical specifications and implementation guidelines designed for lightweight messaging in internet-of-things environments. The site is implemented as a static website, utilizing static site generation and markdown-based content authoring to distribute protocol specifications and technical standards. The resources cover a broad range of industrial messaging and connectivity capabilities, including publish-subscribe routing, quality-of-service del

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

MQTTnet is a .NET library providing a framework for implementing MQTT clients and brokers. It includes a broker implementation for hosting a central message hub that routes messages between connected clients and a client library for publishing and subscribing to messages. The project supports both TCP and WebSocket transport layers, enabling secure data traffic through transport layer security. It allows for the development of custom middleware to intercept, transform, or validate messages as they pass through a server. Capability areas include distributed message routing, persistent connect

libhv is a high-performance C/C++ network library and event-driven I/O framework used to build TCP, UDP, SSL, HTTP, WebSocket, and MQTT clients and servers. It provides a non-blocking event loop for managing network sockets, timers, and system signals across multiple threads. The project is distinguished by its integrated support for specialized network roles, including a full HTTP web server with RESTful routing and middleware, an MQTT messaging client for IoT communication, and the ability to implement SOCKS5 and HTTP proxies. It also features a reliable UDP implementation to ensure ordered

MQTTnet is a comprehensive MQTT library for .NET that supports both client and broker roles in a single codebase. It provides a full-featured broker implementation capable of hosting a server with access control, message interception, session persistence, and support for mixed MQTT protocol versions. The client side offers robust publish-subscribe communication with automatic reconnection that preserves quality-of-service guarantees, ensuring reliable message delivery across network interruptions. The library distinguishes itself with a plugin-based authentication pipeline for validating clie

MQTTX is a cross-platform MQTT client application designed for testing, debugging, and managing MQTT brokers. It supports both MQTT v3.1.1 and v5.0, enables simultaneous management of multiple broker connections, and provides an interactive chat-style interface for publishing and subscribing with configurable quality of service, payload transformation, and topic visualization. The client can be used as a desktop application, a command-line tool, or a self-hosted web client deployable via Docker. What sets MQTTX apart is its integration of AI-assisted workflows, allowing users to generate MQTT

Mosquitto is an MQTT message broker and IoT messaging server designed to route data between publishers and subscribers. It functions as a centralized network hub that enables lightweight communication between distributed sensors, controllers, and other internet-of-things devices. The project includes an MQTT bridging gateway used to link separate brokers, allowing traffic to be routed and synchronized across different network locations or security zones. It also provides a client implementation for connecting to and interacting with the broker. The system manages topic-based message routing

blinker-js is an IoT device communication framework and Node.js library designed to manage bidirectional data exchange between embedded hardware and remote servers or local networks. It functions as an MQTT hardware integration tool that links single-board computers to IoT clouds for remote management and control. The project provides a virtual device widget manager to synchronize hardware state with cloud-based user interface components. This system allows for the mapping of remote UI identifiers to internal software logic, enabling remote IoT control through virtual buttons and input fields

MQTT.js is a JavaScript client library and asynchronous messaging client used to connect to message brokers and exchange data via the MQTT protocol. It provides a broker interface for publishing and subscribing to topics, and includes a command-line interface for interacting with brokers without writing code. The library supports multiple network layers, including TCP, TLS, and WebSockets, and allows for custom WebSocket construction and transport injection to handle specific headers or subprotocols. It implements bandwidth reduction through topic aliasing, which replaces repetitive topic str

uWebSockets is a C++ networking framework that serves as a high-performance WebSocket server library, HTTP web server, and pub-sub messaging system. It provides the infrastructure necessary to handle standard web requests and maintain low-latency, bidirectional connections between clients and servers. The framework is distinguished by its use of template meta-programming for compile-time optimization and zero-copy buffer management to minimize memory latency. It utilizes a backend-agnostic event loop and static route resolution to process network traffic with minimal runtime overhead. The pr

evcc is an open-source home energy management system and solar charging optimization engine. It coordinates solar inverters, electric vehicle chargers, home batteries, and smart devices to route surplus solar energy to load points, optimizing energy use and minimizing grid costs. The platform functions as a multi-protocol charger orchestrator and ISO 15118-2 plug and charge controller, enabling automatic vehicle identification and battery state retrieval. It distinguishes itself through a plugin-based device abstraction layer and protocol-agnostic drivers that unify control across diverse har

This is a Go client library and protocol implementation for interacting with message brokers using the AMQP 0.9.1 standard. It serves as an asynchronous messaging toolkit and message queue client for implementing producer and consumer patterns. The library provides a programmatic interface for managing the full message lifecycle, including publishing, consumption, and delivery acknowledgments. It supports reliable delivery mechanisms such as publishing confirmations and atomic transactions. The project covers the administration of routing topologies through the declaration and binding of que

This project is an open-source software development kit and framework for implementing the Matter smart home standard. It provides a universal IPv6-based application layer and a cluster-based data model to ensure interoperability between diverse smart home devices and controllers. The system is distinguished by its multi-transport network abstraction, which maps Bluetooth LE, Thread, and Wi-Fi implementations to a common layer. It includes specialized tooling for secure device commissioning via QR codes and NFC, as well as a comprehensive over-the-air firmware update system for distributing s

This project is network firmware for the ESP32 that functions as a wireless repeater, NAT router, or wireless bridge to extend WiFi coverage. It can operate as a WiFi range extender, a layer-2 bridge for shared subnets, or a NAT router that creates a private secondary subnet to connect clients to an upstream network. A key differentiator is its ability to act as an enterprise WiFi to PSK converter, translating PEAP-authenticated networks into WPA2-PSK networks for devices that do not support enterprise authentication. Additionally, it includes a network traffic mirroring tool that streams int

Vector is a high-performance observability data pipeline designed to collect, transform, and route logs, metrics, and traces across distributed infrastructure. It functions as a modular engine that decouples data ingestion from processing and transmission, utilizing a component-based architecture to connect diverse sources to multiple destinations. The project distinguishes itself through a focus on reliability and flow control. It implements backpressure-aware data movement to prevent data loss during traffic spikes and utilizes disk-backed event buffering to ensure durability during network

This project is a C++ TCP server framework and educational socket programming guide. It provides a high-performance network library focused on event-driven architecture, implementing a reactor pattern to handle thousands of simultaneous client connections. The framework is distinguished by its multi-threaded event loop, which utilizes a main-sub reactor coordination model to distribute network events across a worker thread pool. It includes an abstraction layer for non-blocking socket I/O and event multiplexing via the epoll system call, decoupling network transport from application business

CAP is a .NET distributed transaction framework and event bus designed to manage asynchronous communication in microservices. It implements the outbox pattern to ensure eventual consistency and reliable message delivery by persisting messages in local database tables until transactions commit. The framework includes a distributed message monitor and web dashboard for tracking the status of sent and received messages. It provides tools for event traffic visualization, distributed request tracing, and the ability to manually trigger retries for failed delivery attempts. The system supports var

This project is a comprehensive Java backend engineering guide and technical reference focused on high-concurrency design, distributed systems, and microservices architecture. It provides detailed strategies for decomposing monolithic applications, managing service discovery, and implementing the architectural patterns required for scalable backend environments. The repository distinguishes itself through an extensive collection of big data algorithmic references and database scaling strategies. It covers memory-efficient techniques for analyzing massive datasets, such as Top-K element extrac

This is a Java library for establishing real-time bidirectional communication with servers using the Socket.IO protocol. It functions as an event-driven communication client that allows Java applications to exchange named events and binary data with a remote server. The library implements both WebSocket and HTTP long-polling transports, providing a fallback mechanism when WebSocket connections are unavailable. It supports namespace-based multiplexing to divide a single physical network connection into multiple logical channels for separating data streams. The project covers a broad range of

Gobot is a robotics framework for the Go programming language designed for developing robotics, drones, and IoT applications. It provides a hardware abstraction layer with standardized drivers to interact with GPIO, I2C, SPI, and PWM interfaces across various single-board computers and microcontrollers. The framework functions as an IoT device orchestrator and BLE device manager, enabling the coordination of multiple sensors, actuators, and Bluetooth Low Energy peripherals. It includes specialized interfaces for drone control, allowing for the management of flight maneuvers and video streams

This project is a high-performance MQTT broker and IoT data platform designed to manage millions of concurrent device connections. It provides a scalable infrastructure for ingesting, processing, and routing telemetry data across distributed systems, utilizing an actor-based concurrency model to maintain high availability and state synchronization across cluster nodes. The platform distinguishes itself through integrated stream processing and edge computing capabilities. It allows users to execute declarative SQL-based rules directly against incoming message streams for real-time filtering, t

This project is a software engineering style guide and a curated collection of architectural patterns and coding standards. It provides a multi-language coding standard to ensure maintainable software across Ruby, Python, JavaScript, and Swift. The project establishes a development workflow specification for version control, continuous integration, and peer review to maintain a linear project history. It also includes a web accessibility framework based on ARIA and WCAG standards, using design tokens and semantic HTML patterns to build inclusive interfaces. The guides cover a broad range of

Mosquitto is a message broker that implements the MQTT protocol to route messages between connected devices and applications. It functions as a central hub for event-driven communication, supporting message exchange over both raw TCP and WebSockets. The software provides a persistent messaging infrastructure by writing message queues and client subscription states to disk, ensuring data recovery following service interruptions. The broker distinguishes itself through its support for distributed system synchronization, allowing for the federation of multiple remote brokers to share data across

Tasmota is a universal firmware platform for ESP8266 and ESP32 microcontrollers, designed to provide local control and management of smart home hardware. It functions as an event-driven automation controller that replaces proprietary factory firmware, allowing users to manage relays, sensors, and lighting systems without relying on external cloud services. The system is built on a modular driver architecture that enables dynamic hardware configuration and peripheral support through a web-based management interface. The platform distinguishes itself through a template-driven hardware mapping s

RocketMQ is a cloud-native distributed messaging platform and streaming engine. It functions as a distributed transactional queue that ensures atomicity between local transactions and message delivery, and serves as an MQTT IoT message broker to bridge lightweight device traffic into high-performance data streams. The system is distinguished by a Kubernetes-native architecture that decouples compute from storage to allow independent scaling of traffic and data retention. It utilizes a tiered storage model to offload older data to remote storage and employs quorum-based replication and automat