Open-source alternatives to Libwebsockets

Muduo is a C++11 event-driven network library and framework designed for building high-concurrency Linux servers. It provides a toolkit for implementing scalable network services and socket communication using non-blocking I/O and asynchronous event processing. The framework implements a multi-threaded TCP server architecture that distributes connection handling across multiple CPU threads to maximize server throughput. This is achieved through a one-loop-per-thread model and a reactor pattern implementation, which dispatch network events from a central demultiplexer to registered handler fun

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

Swift NIO is a low-level, event-driven network framework for the Swift language. It serves as an asynchronous network protocol stack and I/O library designed to build high-performance network servers and clients that handle thousands of simultaneous connections. The framework functions as a high-concurrency network engine that dispatches events across multiple CPU cores. It enables the implementation of custom network protocols by processing raw bytes through a sequence of reusable data transformation handlers. The system provides capabilities for non-blocking I/O multiplexing, asynchronous

HP-Socket is a networking library for building scalable TCP, UDP, and HTTP servers and clients with event-driven I/O and SSL encryption. It provides a high-performance TCP server framework, an HTTP request handler that parses incoming requests and generates responses, and a UDP communication library for low-latency data transfer, all with optional SSL encryption for secure communication. The library is built on a completion-port-based I/O architecture that uses Windows I/O Completion Ports for scalable asynchronous socket operations. It features a connection-pooled agent architecture for mana

Workerman is an event-driven asynchronous socket framework for PHP. It provides the core components necessary to build high-concurrency network servers, including an asynchronous TCP framework, a coroutine library for task management, and dedicated implementations for HTTP and WebSocket servers. The project enables the development of specialized network services using custom frame-based communication protocols. It supports both inbound concurrent server implementation and asynchronous outbound connectivity to remote services. The framework covers a broad range of network programming capabili

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 project is a cross-platform C library designed for implementing MQTT messaging in applications. It serves as an asynchronous networking toolkit that enables resource-constrained systems and distributed components to exchange telemetry data and control signals with messaging brokers. The library distinguishes itself through a state-machine-based protocol handler that manages connection lifecycles and persistent session states, ensuring reliable message delivery even during intermittent network connectivity. It utilizes a background thread to manage network operations, allowing application

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

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

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

Beast is a C++ library for implementing low-level HTTP and WebSocket clients and servers. It functions as an asynchronous networking framework designed to compose non-blocking I/O operations and layered stream stacks for managing concurrent network traffic, specifically utilizing the Boost.Asio asynchronous model. The library provides a comprehensive implementation of the HTTP/1.1 and WebSocket protocols. For HTTP, it includes primitives for parsing and serializing messages with support for chunked transfer encoding, incremental body reading, and request pipelining. Its WebSocket implementati

This is a header-only C++ library that provides implementations for HTTP clients, HTTP servers, and a WebSocket framework. It allows for the creation of network services and the consumption of remote APIs without requiring a separate compilation step or external binary linking. The project features backend-agnostic TLS integration for secure HTTPS and WSS communication and employs a thread-pool model to process concurrent requests. It distinguishes itself with a full-duplex WebSocket state-machine and a middleware-based request pipeline that supports regular-expression path routing. The libr

NuttX is a POSIX-compliant real-time operating system designed for microcontrollers ranging from 8-bit to 64-bit architectures. It provides a deterministic execution environment with a real-time task scheduler and a POSIX embedded kernel to ensure portable code execution across diverse hardware targets. The project distinguishes itself through a comprehensive hardware abstraction layer that provides standardized drivers for I2C, SPI, CAN, and USB across various semiconductor chipsets. It also features an embedded networking stack supporting TCP, UDP, IPv4, and IPv6, alongside industrial proto

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

Twisted is an event-driven networking engine for Python that provides a framework for building asynchronous network applications. At its core, it uses a reactor-based event loop to drive all input and output, dispatching callbacks in a single thread without blocking. The library implements a deferred promise chain for composing asynchronous logic, along with a protocol and factory pattern that separates connection state management from protocol handling, enabling reusable handlers for different network protocols. The framework supports multiple event loops across platforms, including select,

shadowsocks-libev is an event-driven network daemon that provides an encrypted SOCKS5 proxy. It functions as a lightweight proxy server using a non-blocking event loop to route TCP and UDP traffic through encrypted tunnels to bypass network restrictions. The project implements a transparent proxy gateway capable of intercepting outbound packets at the network layer, allowing system traffic to be redirected through the encrypted tunnel without per-application configuration. It also includes a daemon process manager to control multiple proxy server instances as child processes via local communi

Vert.x is a reactive polyglot framework and asynchronous programming library for the Java Virtual Machine. It functions as an event-driven networking framework and toolkit for building non-blocking applications. The system enables the development of high-concurrency network services and event-driven microservices. It supports the creation of reactive services using multiple languages running on the JVM. The framework covers a wide range of capabilities including the management of HTTP and TCP network protocols, non-blocking file system access, and the integration of reactive clients.

Coost is a concurrent network framework and coroutine scheduler designed for building high-performance TCP, HTTP, and RPC services. It provides a set of tools for handling non-blocking IPv4 and IPv6 communication, integrating SSL encryption and a lightweight execution engine that manages concurrent tasks using shared stacks. The project features a specialized JSON RPC implementation for exchanging structured data over encrypted connections and a high-performance logging system. This logging infrastructure supports topic-based routing, frequency filtering, and automated stack trace capture for

ZLMediaKit is a high-concurrency streaming engine designed to function as a protocol gateway and media server. It provides a native development kit for embedding streaming and transcoding capabilities directly into custom applications, supporting the ingestion, distribution, and recording of live video feeds across various network protocols. The platform distinguishes itself through a high-performance architecture that bridges legacy surveillance protocols with modern web-compatible streaming standards. It utilizes a thread-per-core execution model and zero-copy buffer management to maintain

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

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

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

PgBouncer is a lightweight middleware proxy server and connection pooler for PostgreSQL. It acts as a database connection manager and load balancer, reducing system overhead by managing a pool of reusable connections and distributing incoming traffic across multiple backend servers. The project distinguishes itself through a protocol-level proxying approach that handles authentication and TLS encryption without parsing underlying SQL queries. It provides specialized support for mapping named prepared statements across different backend connections and implements a socket-sharing process model

This framework is a distributed systems runtime designed for building fault-tolerant, message-driven microservices and high-performance network applications in PHP. It provides an asynchronous execution environment that utilizes event-loop-based concurrency and promise-based task orchestration to manage high-concurrency workloads without blocking execution threads. The platform distinguishes itself through a unified execution abstraction that manages multi-process and multi-threaded components as isolated, supervised containers. By employing an actor-model approach to process supervision, the

CocoaHTTPServer is a lightweight embedded web server designed to handle incoming network requests and serve local application content. The project implements Bonjour-based service discovery to broadcast server availability on local networks and supports WebDAV for remote file management, allowing files to be created, moved, and edited over HTTP. Network security is handled through certificate-based TLS encryption and password-based resource authentication. Request routing is managed via a delegate-based system, while concurrent connections are handled using Grand Central Dispatch.

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