Trystero helps browsers discover each other and communicate directly with peer-to-peer data, files, audio, video, and presence. No accounts. No signaling server to deploy. Just import and connect.
npm i trystero
Trystero is an open source JavaScript library that makes WebRTC peer discovery and peer-to-peer communication feel simple. Use it to build multiplayer web apps, collaborative tools, browser-to-browser file transfer, video chat, local-first sync, and realtime presence without running your own matchmaking infrastructure.
Import Trystero, join a room, and start sending peer-to-peer messages. Peers find each other automatically through serverless signaling.
// Import Trystero
import {joinRoom} from 'trystero'
// Join a room with your app ID and a room ID
const room = joinRoom(
{appId: 'my-app'},
'room-id'
)
let peerCount = 0
// Handle when a peer joins
room.onPeerJoin = peerId => {
console.log(`${peerId} joined!`)
peerCount++
}Trystero abstracts away all the complexity of WebRTC and peer discovery. Send files, video streams, and any other data with a clean and easy API.
All data sent between peers is end-to-end encrypted. No intermediary can read your users’ messages. You can opt into more advanced identity verification features too.
Peers discover each other through decentralized infrastructure like Nostr, MQTT, BitTorrent, and more. You can also run your own relay if you’re into that kind of thing.
Actions are typed channels. Create as many as you need. Send strings, objects, binary data like files, or audio/video streams.
// Create an action to send and receive cursor positions
const cursor = room.makeAction('cursor')
// Send the cursor position to peers when the mouse moves
document.onmousemove = e =>
cursor.send({x: e.clientX, y: e.clientY})
// Receive the cursor position from other peers
cursor.onMessage = (pos, {peerId}) =>
movePeerCursor(peerId, pos)
// Using TypeScript? Add a type
type CursorPosition = {x: number; y: number}
const typedCursor =
room.makeAction<CursorPosition>('cursor-typed')Stream audio and video directly between browsers. Build presence indicators, voice chat, or collaborative editing.
// Grab the user's camera stream
const stream = await navigator.mediaDevices.getUserMedia({
audio: true,
video: true
})
// Send the stream to peers in the room
room.addStream(stream)
// Send the stream to peers who join later
room.onPeerJoin = peerId => {
room.addStream(stream, {target: peerId})
}
// Handle streams from other peers
room.onPeerStream = (stream, peerId) =>
// Connect the stream to a video element
videoElements[peerId].srcObject = streamActions can also work like request/response channels. Ask one peer for a value, wait for a reply, or collect answers from a whole room.
// Create a request/response action
const availability = room.makeAction('availability', {
kind: 'request',
onRequest: ({date}) => calendar.isFree(date)
})
// Ask a specific peer and wait for their answer
const isFree = await availability.request(
{date: '2026-05-04'},
{
target: teammateId,
timeoutMs: 1000
}
)
if (isFree) {
showAvailable(teammateId)
}Trystero is open source, works across modern browsers and devices, and is ready to use in JavaScript and TypeScript projects.