PeerServer

PeerJS uses a signaling server to broker connections between peers. By default, it connects to the free PeerJS Cloud server. For production, you can host your own.

Quick Start

npm

npm install peer

Yarn

yarn add peer

pnpm

pnpm add peer

Bun

bun add peer

server.js

const { PeerServer } = require("peer");

const server = PeerServer({ port: 9000, path: "/myapp" });

server.on("connection", (client) => {
  console.log("Client connected:", client.getId());
});

server.on("disconnect", (client) => {
  console.log("Client disconnected:", client.getId());
});

node server.js

Connect from the Client

Point your Peer to your server:

const peer = new Peer({
  host: "localhost",
  port: 9000,
  path: "/myapp",
  secure: false, // Use true with HTTPS
});

Server Options

Option	Type	Default	Description
port	number	9000	Port to listen on
path	string	"/"	Path prefix
key	string	"peerjs"	API key clients must provide
proxied	boolean	false	Set true if behind a reverse proxy
expire_timeout	number	5000	Timeout for messages (ms)
alive_timeout	number	60000	Timeout for heartbeat (ms)
allow_discovery	boolean	false	Allow clients to list all peer IDs

Express Integration

PeerServer can be mounted as Express middleware:

const express = require("express");
const { ExpressPeerServer } = require("peer");

const app = express();
const server = app.listen(9000);

const peerServer = ExpressPeerServer(server, {
  path: "/myapp",
});

app.use("/peerjs", peerServer);

peerServer.on("connection", (client) => {
  console.log("Connected:", client.getId());
});

Docker

Run PeerServer with Docker:

docker run -p 9000:9000 peerjs/peerjs-server

Or with custom options:

docker run -p 9000:9000 peerjs/peerjs-server \
  --port 9000 \
  --path /myapp \
  --key myapikey

Production Considerations

• HTTPS: Always use SSL in production. Set secure: true on the client.
• TURN servers: PeerServer only handles signaling. You still need TURN servers for peers behind symmetric NATs. See the FAQ for configuration.