Open-source alternatives to ESPAsyncWebServer

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

GCDWebServer is a lightweight HTTP 1.1 server for iOS, macOS, and tvOS. It serves as an embedded network server for Apple platforms, allowing developers to handle incoming requests through custom synchronous or asynchronous handlers. The project includes a WebDAV server implementation for remote file management, directory browsing, and synchronization using standard network clients. It also provides a web-based file manager that enables users to upload, download, and organize files within an application sandbox via a browser. Additional capabilities include gzip compression, JSON processing,

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

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

Gevent is a Python coroutine concurrency library and asynchronous task manager designed for high-concurrency I/O tasks. It provides a cooperative networking framework for building asynchronous TCP, UDP, and HTTP servers, as well as a WSGI web server implementation for hosting web applications. The project is distinguished by its standard library monkey-patching tool, which replaces blocking synchronous functions with cooperative versions to enable asynchronous behavior in third-party code. This allows for a cooperative multitasking workflow where the system yields execution during I/O waits t

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

Ratchet is a PHP library for building asynchronous WebSocket servers that handle persistent, bidirectional communication between clients and the server. It provides a complete server-side WebSocket implementation, including protocol handshake negotiation, message framing over TCP, and an event-loop-based concurrency model that manages thousands of simultaneous connections without blocking. The library implements a connection registry pattern for tracking all active WebSocket sessions, enabling the server to broadcast or unicast messages to any connected client on demand. It relies on non-bloc

Salvo is a comprehensive Rust web framework for building asynchronous HTTP servers and web applications. It features a hierarchical web router that uses a tree-based structure to map requests to handlers and an asynchronous middleware pipeline based on the onion model for request and response pre- and post-processing. The framework is distinguished by its native support for modern network protocols, including a QUIC-based HTTP/3 implementation alongside HTTP/1 and HTTP/2. It includes an integrated OpenAPI documentation generator that extracts schemas directly from handler signatures to produc

EasySwoole is a high-performance asynchronous PHP framework designed for building event-driven networks and persistent memory applications. It functions as a toolkit for developing distributed microservices and asynchronous servers capable of handling concurrent HTTP, TCP, UDP, and WebSocket connections. The framework distinguishes itself through a persistent memory process execution mode that eliminates the overhead of repetitive file loading and invocation during request handling. It provides built-in support for distributed systems via remote procedure call implementations and service disc

This project is a technical study and analysis guide focused on the internal architecture of Node.js. It provides an in-depth examination of the runtime, focusing on how the engine manages memory handles, executes asynchronous operations, and implements core module logic. The guide specifically analyzes the integration of native C++ classes and functions into JavaScript and documents the behavior of the libuv event loop. It includes detailed references for optimizing performance by identifying V8 compiler bailouts and profiling execution to improve resource efficiency. The material covers a

Vibora is an asynchronous Python web framework and built-in HTTP server designed for building high-performance web applications. It utilizes an asynchronous event loop and coroutines to process network requests and serve responses without requiring external server wrappers. The project features a high-performance asynchronous schema validator for request integrity, a non-blocking template engine with support for hot-reloading, and a WebSocket communication server for bidirectional real-time data exchange. The framework covers a broad range of capabilities, including modular route management

Micro is a minimalist Node.js web framework designed for creating lightweight, asynchronous HTTP services and JSON APIs. It serves as a low-footprint library for deploying asynchronous handlers focused on high request volumes and minimal overhead. The framework utilizes a functional request and response model, routing traffic to a single exported asynchronous function as the primary entry point. It specializes in processing incoming JSON requests and returning formatted responses with automated error handling. Core capabilities include request body parsing for JSON, plain text, and binary bu

CocoaAsyncSocket is a networking library for macOS and iOS that provides core components for managing asynchronous TCP and UDP streams. It implements non-blocking network communication to maintain application responsiveness during data transfers, featuring a delegate-based system for managing connection streams and packet handling. The library includes a secure communication layer that wraps TCP sockets to apply encryption standards, protecting client and server traffic from unauthorized interception. Its capabilities cover non-blocking connection management for both stream-based TCP and pac

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

Play is a full-stack reactive web framework for Java and Scala. It provides a comprehensive development platform for building scalable web applications and RESTful APIs using a stateless and non-blocking architecture designed for high concurrency. The framework emphasizes high-velocity development through dynamic code reloading, which allows developers to update applications and verify changes without performing a full restart. Its capability surface covers the construction of JSON-based web endpoints, server-side logic for the JVM, and the implementation of scalable web architectures.

This is a self-hosted WebSocket server for Laravel applications designed to provide real-time communication and replace third-party managed messaging services. It provides a server-side PHP implementation of the WebSocket standard, enabling full-duplex communication between clients and servers. The project implements a Pusher-compatible protocol to integrate with existing frontend client libraries. It includes a dedicated debug dashboard for monitoring active connections, tracking network traffic, and analyzing real-time server performance. The system supports Laravel event broadcasting and

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

Nonebot2 is an asynchronous Python framework for building event-driven chatbots across multiple messaging platforms. It centers on a non-blocking event bus and a driver-based adapter system that unifies different messaging protocols into a single consistent interface. The framework utilizes a modular plugin architecture, allowing for the discovery and loading of third-party extensions to add new event handlers and system capabilities. It distinguishes itself with a type-annotation based dependency injection system that automatically resolves and provides required service objects to handlers a

Curio is a Python library for structured concurrency and asynchronous network programming. It serves as a framework for handling thousands of simultaneous TCP connections using non-blocking sockets and high-throughput I/O. The library organizes asynchronous operations into a hierarchy of parent and child coroutines to ensure reliable termination and cleanup of dependent tasks. It provides a toolkit for coordinating these concurrent operations through the use of task groups and timeouts. The framework covers a broad range of concurrency management capabilities, including inter-task communicat

This project is an asyncio database abstraction layer that provides a common interface for performing non-blocking database operations in Python. It functions as an asynchronous database driver wrapper and a SQL expression builder, allowing for the construction of raw SQL strings from structured Python objects. The library includes an asyncio connection pool manager that utilizes task-local storage to handle connection lifecycles and reduce resource overhead. It also serves as an async database transaction manager, wrapping operations in atomic transactions and savepoints to maintain data int

Uvicorn is an ASGI web application host designed for asynchronous Python web development. It serves applications through a standardized asynchronous server gateway interface to handle non-blocking network traffic and high-concurrency requests. The server manages both HTTP and WebSocket traffic, including the handshaking process required to establish persistent, full-duplex communication channels for real-time data exchange. For development workflows, the project includes a hot-reload mechanism that monitors the filesystem for source code changes and automatically restarts the server process.

Quart is an asynchronous Python web framework that implements the ASGI specification. It is used to build high-performance HTTP and WebSocket services, JSON REST APIs, and web applications using async and await syntax for non-blocking request handling. The framework supports persistent bidirectional communication via WebSocket API servers and enables the proactive delivery of assets through HTTP server push. It also includes a template engine for rendering dynamic HTML web pages and supports incremental request and response streaming to manage large payloads. General capabilities cover reque

netty-socketio is a Java implementation of a Socket.IO server designed for real-time bidirectional communication between clients and servers. It functions as a real-time event engine and WebSocket communication server, utilizing the Netty network framework to manage high-performance socket connections. The project enables distributed socket server scaling by acting as a distributed message broker. It synchronizes client states and broadcasts messages across multiple server nodes through the use of an external data store. The system manages traffic via namespace-based connection routing and r

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

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

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 is a non-blocking network client for Java applications that provides asynchronous HTTP request capabilities and bidirectional WebSocket connectivity. It leverages a Netty-based architecture to handle high volumes of network input and output. The library utilizes native transport abstractions such as Epoll, KQueue, and io_uring to reduce system latency. It supports HTTP/2 multiplexing to run multiple concurrent request-response streams over a single connection and provides automatic response body decompression for various formats. Core capabilities cover the management of complex network