WebSocket Libraries for C++: Overview and Usage Examples

WebSocket libraries for C++: complete guide

WebSocket is a protocol that provides full-duplex communication between a client and a server over a single TCP connection. Unlike HTTP, WebSocket allows the server to send data to the client without a preliminary request, making it ideal for chats, games, stock quotes, and other real-time applications. In the C++ ecosystem, there are several mature libraries that implement this protocol. In this article, we will look at three of the most popular ones: Boost.Beast, uWebSockets, and libwebsockets.

1. Boost.Beast (recommended)

Boost.Beast is a library based on Boost.Asio that provides HTTP and WebSocket protocols. It is part of the official Boost distribution (starting from version 1.66). Main advantages: strong typing, full support for the RFC 6455 standard, integration with Asio for asynchronous operation.

Main features:

• Synchronous and asynchronous WebSocket clients/servers
• Support for frames, pings/pongs, connection closure
• Operation over TLS (via Boost.Asio SSL)
• Cross-platform (Linux, Windows, macOS)

WebSocket server example (asynchronous):

#include <boost/beast/core.hpp>#include <boost/beast/websocket.hpp>#include <boost/asio/ip/tcp.hpp>#include <cstdlib>#include <functional>#include <iostream>#include <string>

namespace beast = boost::beast;namespace websocket = beast::websocket;namespace net = boost::asio;using tcp = net::ip::tcp;

void do_session(tcp::socket& socket) {    try {        websocket::stream<tcp::socket> ws{std::move(socket)};        ws.accept();

        for(;;) {            beast::flat_buffer buffer;            ws.read(buffer);            auto msg = beast::buffers_to_string(buffer.data());            std::cout << "Received: " << msg << std::endl;

            // Echo response            ws.text(ws.got_text());            ws.write(buffer.data());        }    } catch(beast::system_error const& se) {        if(se.code() != websocket::error::closed) {            std::cerr << "Error: " << se.code().message() << std::endl;        }    }}

int main() {    try {        net::io_context ioc{1};        tcp::acceptor acceptor{ioc, {tcp::v4(), 8080}};

        for(;;) {            tcp::socket socket{ioc};            acceptor.accept(socket);            std::thread{std::bind(&do_session, std::move(socket))}.detach();        }    } catch(std::exception const& e) {        std::cerr << "Error: " << e.what() << std::endl;        return EXIT_FAILURE;    }    return EXIT_SUCCESS;}

2. uWebSockets (uWS)

uWebSockets is a high-performance library focused on maximum speed and minimal memory consumption. It is written in C++17 and uses its own event loop (not Boost.Asio). It is well suited for microservices and applications with thousands of concurrent connections.

Key features:

• Very low latency (~2-3 microseconds per message)
• Support for WebSocket, HTTP, and SSE (Server-Sent Events)
• Built-in TLS support (via OpenSSL or BoringSSL)
• No external dependencies (except OpenSSL for TLS)

Simple WebSocket server example:

#include "App.h"

int main() {    uWS::App().ws<int>("/*", {        .open = [](auto* ws) {            std::cout << "Client connected" << std::endl;            ws->send("Welcome!", uWS::OpCode::TEXT);        },        .message = [](auto* ws, std::string_view message, uWS::OpCode opCode) {            std::cout << "Received: " <<