Open-source alternatives to MQTTnet

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

FastStream is an asyncio message broker framework for building event-driven applications in Python. It provides a unified interface and a multi-broker messaging abstraction layer that translates generic producer and consumer calls into broker-specific APIs. The framework features a built-in dependency injection container and uses decorators to route messages to asynchronous handler functions. It includes a documentation generator that extracts channel definitions and message formats from code to produce standardized AsyncAPI specifications. The project supports integration with Kafka, Rabbit

This project is a lightweight MQTT client library for Arduino boards, specifically designed for embedded systems utilizing an Ethernet Shield. It functions as an embedded messaging client that allows hardware devices to publish and subscribe to topics on a remote message broker. The library provides core MQTT integration, including broker connection management and the maintenance of server heartbeats. It supports topic-based message publishing and subscription management, enabling the registration of listeners to trigger functions upon message arrival. The system covers network connection co

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

This project is a Java messaging software development kit designed to facilitate real-time data exchange between applications and message brokers. It functions as an MQTT client library, providing the necessary tools to implement publish-and-subscribe messaging patterns within distributed systems and internet-connected device environments. The library distinguishes itself through its focus on resilient network connectivity and reliable message delivery. It manages persistent connections through internal state machines that handle automatic reconnection and keep-alive heartbeats, ensuring stab

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

Easegress is a cloud-native traffic orchestration platform that functions as a multi-protocol API gateway and service mesh proxy. It routes, transforms, and orchestrates HTTP and MQTT traffic through configurable filter chains, providing high availability, security controls, and resilience for backend services. The platform integrates with service discovery systems like Kubernetes, Consul, and Eureka to dynamically route traffic to discovered services with automatic failover and health monitoring. The system distinguishes itself through a pipeline-based filter chain architecture where request

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

This project is a reference library of firmware examples and a development framework for creating embedded C applications on the RP2040 microcontroller. It provides a collection of hardware peripheral drivers and foundational patterns for managing system resources in resource-constrained environments. The library features reference implementations for programmable I/O state machines, allowing for the creation of custom hardware-level protocols. It also provides a multicore embedded framework to distribute computational workloads across multiple processor cores using symmetric processing. The

This library is an MQTT client implementation designed for resource-constrained embedded systems, specifically targeting ESP8266 microcontrollers. It provides a framework for establishing persistent network connections to exchange data with remote messaging brokers, enabling reliable communication for IoT devices. The library distinguishes itself through its ability to maintain simultaneous connections to multiple independent messaging brokers, facilitating complex data routing across distributed environments. It utilizes a state-machine approach to manage connection lifecycles, including aut

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

Emitter is a distributed pub-sub platform and message brokering system that decouples senders and receivers through topic-based routing. It functions as an MQTT message broker and WebSocket communication server, enabling real-time data exchange between hardware devices and web-based clients. The system acts as a secure channel orchestrator and message persistence engine. It ensures delivery through a storage system that buffers historical messages and queues data for offline subscribers. Access to these data streams is managed via time-limited permission keys that enforce granular read and wr

ejabberd is a multi-protocol communication gateway and scalable server that implements XMPP for instant messaging and presence. It serves as a federated messaging platform, enabling interoperable communication and user discovery between different remote servers. The project functions as an MQTT message broker for lightweight IoT device communication and a SIP signaling server for managing voice and multimedia signaling traffic. It allows for the hosting of multiple domains on a single instance using virtual hosting to isolate configurations and prevent username conflicts. The system provides

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

Flamingo is a self-hosted instant messaging platform and collaborative communication suite. It provides a centralized backend for user authentication and message routing, enabling real-time text and multimedia exchange for distributed teams. The platform integrates a remote desktop tool for administering sessions directly within the communication flow and utilizes a store-and-forward system to ensure files and messages are delivered to offline users. It also includes an automated client update system that detects and installs software updates across supported desktop operating systems. The s

Netpoll is an event-driven network framework and non-blocking I/O library designed to manage concurrent TCP and Unix domain socket connections. It utilizes a non-blocking event loop to monitor file descriptors and trigger callbacks for read and write events, serving as a high-performance socket manager and TCP network poller. The framework optimizes throughput across CPU cores by distributing incoming network connections across multiple pollers. It implements zero-copy networking primitives, using linked buffers and specialized memory management to read and write data while minimizing memory

MobileIMSDK is an open-source instant messaging framework that provides reliable real-time message delivery across iOS, Android, Java, HarmonyOS, and web platforms. At its core, it offers a unified communication layer that transparently supports UDP, TCP, and WebSocket transports, enabling developers to send and receive messages without managing protocol differences or connection state. The framework includes an automatic reconnection engine that detects network outages and restores connections without manual intervention, with built-in message retransmission and deduplication to guarantee exa

Janet is a Lisp-based dynamic programming language featuring a register-based bytecode virtual machine and an embeddable scripting engine. It functions as a fiber-based concurrency runtime and includes a parsing engine based on Parsing Expression Grammars. The project is distinguished by its ability to be integrated into C or C++ applications via a minimal header interface. It utilizes a Lisp-style macro system for compile-time code transformation and employs prototype-based table inheritance for object-oriented behavior. The runtime covers a broad set of capabilities, including asynchronous

Mpush is a real-time message push system and encrypted messaging gateway designed to deliver instant notifications to mobile and web clients. It functions as a session management service and a network traffic controller, utilizing persistent network connections to ensure updates reach users without manual screen refreshing. The system includes an HTTP reverse proxy that routes external domain requests to internal IP addresses with integrated connection timeout management. It maintains communication stability through a persistent session manager that tracks client heartbeats and session expira

gnet is a high-performance event-driven networking framework for Go, designed for building scalable TCP, UDP, and Unix socket servers. It functions as a non-blocking socket manager and multi-reactor network engine that handles thousands of simultaneous connections with low memory overhead. The framework distinguishes itself by using a multi-reactor architecture that distributes I/O across multiple event loops pinned to operating system threads to minimize context switching. It employs edge-triggered polling to reduce system call frequency and utilizes elastic ring-buffers to minimize allocati

BotsApp is a WhatsApp automation tool and userbot framework designed to add custom capabilities and automation to a standard WhatsApp user account. It functions as a personal assistant bot that executes automated actions and manages conversations within the platform. The project provides a scriptable interface for automating account tasks and extending the features of a personal profile. This allows for the implementation of a userbot to handle personal messaging automation and repetitive account workflows.

The Lounge is a self-hosted, web-based IRC client that functions as a persistent bouncer replacement, keeping users connected to IRC servers even when their browser is closed or device is offline. It runs as a Node.js backend with a WebSocket bridge that relays IRC events and commands between the server and browser, and includes a built-in HTTP and HTTPS server for direct TLS termination without an external reverse proxy. The client supports multiple user accounts on a shared server installation, with LDAP authentication for credential validation. It maintains persistent server-side IRC conne

Undertow is a Java HTTP web server and non-blocking I/O server implementation. It functions as a Jakarta Servlet container and a WebSocket server, providing the infrastructure to execute standardized servlet components and maintain persistent full-duplex communication channels for real-time data exchange. The project is characterized by an asynchronous architecture that utilizes a non-blocking I/O model to handle large numbers of concurrent connections. It incorporates buffer-pooling mechanisms and zero-copy data transfers to reduce memory allocation and garbage collection pressure. The syst

Boost is a collection of portable, high-performance source libraries that extend the C++ standard library. It provides a wide range of reusable components, data structures, and algorithms designed to add capabilities to the base language across different platforms. The project is distinguished by its extensive focus on compile-time template metaprogramming and generic programming. It implements advanced architectural patterns such as policy-based design, concept-based type validation, and the use of SFINAE for conditional template resolution to minimize runtime overhead. The library covers a

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

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