Open-source alternatives to Libuv

Asio is a C++ library for performing network and low-level I/O operations using a consistent asynchronous model that avoids blocking program execution. It provides a portable, cross-platform interface for network socket communication across different operating systems, and manages multiple asynchronous operations without requiring explicit thread management or locking. The library implements a proactor-based asynchronous model where operations post completion handlers to a queue for later execution, and wraps operating system I/O multiplexing mechanisms like epoll, kqueue, IOCP, and select in

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

Mongoose is an embedded networking library providing TCP/IP stacks, web server hosting, and IoT device connectivity. It enables microcontrollers and desktop systems to implement network protocols including HTTP, WebSocket, and MQTT. The project provides a bare-metal TCP/IP stack for environments without a native operating system and includes built-in TLS and ECC encryption to secure network traffic. It features a binary-embedded file system to serve web content directly from the executable and supports over-the-air firmware updates for managing device fleets. Additional capabilities cover as

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

Handy is a C++11 network server framework and event-driven networking engine designed for building high-performance concurrent TCP and UDP servers. It functions as an asynchronous I/O library and an HTTP server implementation that separates asynchronous network I/O from synchronous business logic to simplify server development. The framework distinguishes itself by utilizing platform-specific event notifications to manage millions of simultaneous network connections and providing an SSL/TLS network wrapper for encrypted asynchronous data transmission. It implements a half-sync/half-async proc

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.

Smol is a lightweight Rust asynchronous runtime and task executor. It provides a suite of foundational tools for scheduling and executing asynchronous futures, managing background workloads, and handling non-blocking network and file operations. The project includes a compatibility layer for adapting asynchronous types and execution contexts, enabling futures to run across different runtime ecosystems. It also features a mechanism to offload synchronous I/O and CPU-intensive operations to dedicated worker thread pools to prevent runtime stalls. Its capabilities cover non-blocking network I/O

WinFSP is a framework for implementing custom file systems on Windows. It enables the creation of user-mode file systems that appear as standard disk drives or network shares to the operating system, allowing developers to implement file system logic in user space via a proxy architecture that avoids the need for custom kernel code. A primary differentiator is its FUSE compatibility layer, which maps POSIX-based file system calls to native Windows requests. This allows existing file systems written for the FUSE API to be ported to Windows and Cygwin environments. The project covers a wide ra

Mio is a low-level I/O library for Rust that provides an event-driven framework for monitoring multiple network sockets and file descriptors. It acts as a portable wrapper for operating system native polling systems, including epoll, kqueue, and IOCP, allowing applications to trigger events when resources are ready for reading or writing without blocking the execution thread. The library provides a non-blocking socket interface for managing TCP, UDP, and Unix sockets. It distinguishes itself through a vectored I/O implementation, enabling scatter-gather reads and writes across multiple buffer

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

ReactPHP is an asynchronous runtime and event-driven I/O framework for PHP. It provides an environment for executing concurrent tasks through a central event loop implementation and reactor pattern, allowing applications to handle multiple operations without pausing the main execution thread. The project includes a specialized asynchronous socket library for TCP, UDP, and TLS communication, alongside a non-blocking HTTP server and client for streaming web requests and responses. Its capability surface covers asynchronous control flow via promises and fibers, non-blocking network connectivity

This project is a keyboard-driven terminal file manager designed for efficient navigation and manipulation of local and remote filesystems. It functions as both a standalone console file explorer and a versatile file picker, allowing users to select paths and pass them to external shell commands or system utilities for automated workflows. The application distinguishes itself through a highly modular architecture that supports compile-time feature flagging and static binary compilation, ensuring a minimal memory footprint and portability across environments. Users can extend its core function

Okio is a Java I/O library providing a set of tools for efficient byte-stream processing and file system operations. It functions as a buffered byte stream handler and streaming data transformer, utilizing a cross-platform file system API to manage data movement. The project is distinguished by its use of pooled mutable byte buffers that treat sequences as queues to reduce memory copying and garbage collection churn. It further decouples file operations from the host operating system through an abstraction-based file system, allowing for consistent path manipulation and atomic operations acro

EventMachine is a reactor-pattern network framework for Ruby that provides an asynchronous I/O library for performing non-blocking network and file operations. It functions as a network server framework used to build scalable TCP and UDP servers and clients that process multiple simultaneous requests. The framework implements a concurrency model that dispatches network events to registered handlers using a single-threaded event loop. This approach allows for the management of high-concurrency network connections without the overhead of multi-threaded programming. The library covers the devel

fsnotify is a cross-platform filesystem notification library that provides a programming interface for tracking file and directory changes within Go applications. It utilizes native kernel notification interfaces to detect events such as file creation, deletion, and attribute updates, allowing developers to integrate real-time monitoring into their software. The library distinguishes itself by providing a unified abstraction layer that normalizes disparate kernel APIs into a consistent event stream. It manages high-volume activity through non-blocking event polling and internal memory bufferi

This project is a detailed analysis and study of the Nginx source code, focusing on high-performance server architecture and function call flows. It serves as a technical examination of the internal C implementation used to build high-concurrency networking systems. The project deconstructs the internal mechanisms of the web server, including the multi-process master-worker model, event-driven asynchronous I/O, and non-blocking socket communication. It analyzes the phase-based request processing lifecycle, from URI matching and header parsing to final content generation. The study covers a b

cppcoro is a C++ coroutine library and concurrency toolkit providing primitives for asynchronous tasks, lazy generators, and non-blocking execution. It functions as an asynchronous I/O framework for managing network sockets and file operations through an event loop. The library features a work-stealing thread pool for distributing tasks across multiple cores and a set of async generators for producing lazy sequences of values both synchronously and asynchronously. It includes a concurrency toolkit with async mutexes, latches, and shared tasks to coordinate multi-threaded execution. Its capab

Drogon is a high-performance, cross-platform C++ framework designed for building asynchronous web services and server-side applications. It functions as a multi-threaded, event-driven server engine that manages concurrent network traffic and WebSocket connections with minimal latency. By leveraging non-blocking input/output and native code compilation, the framework provides a foundation for scalable applications that operate efficiently across diverse hardware architectures. The framework distinguishes itself through its compile-time template rendering, which transforms dynamic HTML views in

threads.js is a JavaScript worker thread library and asynchronous task orchestrator designed to offload CPU-intensive tasks to background threads. It functions as a cross-platform worker pool and a TypeScript worker runner that automatically transpiles and executes TypeScript files within separate threads. The project distinguishes itself by providing a unified worker API that allows for cross-platform execution across different JavaScript environments. It includes a specialized worker data serialization tool to pass complex class instances and binary data between threads, and supports inlini

The C++ REST SDK is a library for asynchronous HTTP and RESTful communication in native C++ applications. It provides a non-blocking network client for sending requests and receiving responses, a JSON parser for serializing and deserializing data, and a WebSocket client library for real-time, full-duplex communication. The project includes a dedicated OAuth2 authentication client to manage access tokens and authorization flows for secure communication with protected cloud resources. It utilizes a task-based asynchronous model to coordinate background operations and keep application interfaces

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

This project is a structured Node.js programming course and educational guide designed to teach JavaScript backend development. It provides a sequence of workshops and interactive tutorials that focus on the fundamentals of the Node.js runtime and its core modules. The material emphasizes asynchronous programming, specifically covering non-blocking I/O, callback patterns, and event-driven architecture. It includes a practical exploration of the core API for managing network applications, file system operations, and binary data. The curriculum covers module management and dependency resolutio

evpp is a C++ network library and framework designed for building high-performance network services using TCP, UDP, and HTTP protocols. It provides an asynchronous event loop to manage nonblocking I/O operations and concurrent network connections across multiple threads. The framework includes specialized tools for asynchronous DNS resolution and a system for asynchronous task scheduling using a managed thread pool. It also features a nonblocking HTTP server and client with integrated connection pooling. The project covers low-level transport layer connectivity for TCP and UDP, as well as hi

s2n is a C-based security library and TLS protocol implementation that serves as a secure network transport layer. It provides a modular cryptographic backend interface to encrypt data streams, manage handshakes, and handle mutual authentication between peers. The project focuses on post-quantum cryptography, integrating quantum-resistant key exchange and digital signatures to protect connections against future computing threats. It distinguishes itself through security hardening measures, such as memory-locked secret storage to prevent keys from being swapped to disk and timing-attack mitiga

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

userver is a comprehensive C++ backend application platform and asynchronous framework designed for building scalable microservices. It provides a high-performance execution environment for deploying services that communicate via gRPC and HTTP using a middleware-based request pipeline. The platform distinguishes itself through a distributed service orchestration toolset that manages shared state, distributed locking, and dynamic configuration updates without requiring process restarts. It utilizes a coroutine-based asynchronous execution model and event-loop network I/O to handle high-concurr

Textual is a Python TUI framework and asynchronous UI library used to build interactive text user interfaces. It provides a component-based architecture for creating cross-platform applications that run in both terminal and web browser environments. The framework distinguishes itself by utilizing a CSS-based layout engine to apply visual styles to widgets and a command palette interface for discovering and executing application functions. It also supports hosting terminal-based interfaces on the web to enable remote access via a standard browser. The toolkit covers a broad range of capabilit