@ezez/ws-server

Type-safe WebSocket server with built-in authentication and reply tracking. Server-side part of the @ezez/ws-client / @ezez/ws-server pair.

Built on top of ws.

Features

• Type-safe messaging - define your events as TypeScript types, get full type checking on both sending and receiving
• Built-in authentication - every client goes through an auth flow before exchanging messages. You can validate tokens, check credentials, or simply accept everyone - it's up to your callback
• Reply tracking - send a message and register a callback for when the client replies to that specific message, enabling request-response patterns over WebSocket
• Flexible server modes - run standalone, attach to an existing HTTP server (Express, Fastify, etc.), or handle WebSocket upgrades manually
• Broadcasting - send a message to all connected clients with a single call
• Data flexibility - send plain text or binary data. Mix them together. Exchange any data type, including undefined, bigint, Date or your own instances

Client features

• tbd

Installation

npm install @ezez/ws-server

You also need @ezez/ws-client on the client side. The two libraries use a shared binary protocol and must be used together.

Quick Example

import { EZEZWebsocketServer } from "@ezez/ws-server";

type FromClient = {
    ping: [message: string];
};

type FromServer = {
    pong: [message: string];
};

const server = new EZEZWebsocketServer<FromClient, FromServer>(
    { port: 8080 },
    {
        onAuthRequest: async (client, authKey) => authKey === "secret",
        onAuthOk: (client) => {
            client.send("pong", ["connected!"]);

            client.on("ping", (args, reply) => {
                const [message] = args;
                reply("pong", [`you said: ${message}`]);
            });
        },
    },
);

await server.start();

Goals

• Simplicity - a thin, opinionated wrapper over ws that removes boilerplate without hiding the WebSocket
• Type safety - catch event name typos and argument mismatches at compile time, not at runtime
• Built-in auth - authentication is part of the protocol so you never forget to handle it

Non-goals

• Not a Socket.IO replacement - no rooms, namespaces, or channel abstractions. If you need to group clients, manage that in your application code
• No HTTP fallback - WebSocket only, no long-polling or SSE. If the client can't establish a WebSocket connection, this library won't help

Documentation

Full documentation is available here: https://ezez.dev/docs/ws-server/latest/

License

MIT