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Realtime

Every change, in every browser, as it happens.

Your function publishes on a channel and every browser connected to it gets the message at once. You see who is connected, browsers can message each other, and a SQL database's table changes go to channels too. There is no WebSocket server to write or run.

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What you get

  • Channels

    A channel is a name your function and the browser agree on, such as room-1. There is nothing to create: the first connection or message brings it to life.

  • Publish from anywhere

    With env.REALTIME.publish from a function, or from the API, the CLI and MCP. Each message reaches every open connection once, in the order it was sent.

  • Presence

    Each browser gets the channel's connected users when it joins, and sees others join and leave as it happens. A function asks with env.REALTIME.presence.

  • Publish from the browser

    With a token that has publish: true, the browser sends messages itself, and everyone else on the channel gets them with the sender in from. For chat, live cursors or typing indicators.

  • Short-lived tokens

    A browser connects only with a token your function makes for one channel and one user, for 10 minutes by default and an hour at most. The signing key is in the project's secrets; rotate it and earlier tokens stop working.

  • Table changes

    Each insert, update and delete in the tables you choose goes to a channel once committed: every change once, in commit order. Switched on per database, and off by default.

  • One WebSocket, nothing to install

    The browser connects to one address with its own WebSocket. Messages are plain JSON with a type: presence, join, leave, message and change.

  • Channels per environment

    Production, previews and development each have their own channels, so a preview's message never reaches production's users.

  • Calm deploys

    On a deploy or a move, a connection closes with code 1012 so the browser reconnects. Adding a server moves no channel.

  • See your channels

    Active channels, connections, the last hour's messages and each channel's connected users in the dashboard, with a test message from there. Daily usage with peak connections.

A chat channel

Your function makes each user a token; the browser connects with it, sees who is connected and sends messages itself.

export default {
  async fetch(request, env) {
    const { pathname } = new URL(request.url)

    if (pathname === "/token") {
      const user = await currentUser(request) // your own sign-in
      return Response.json(await env.REALTIME.token({ channel: "room-1", user, publish: true }))
    }

    if (pathname === "/announce" && request.method === "POST") {
      const { delivered } = await env.REALTIME.publish("room-1", await request.json())
      return Response.json({ delivered })
    }

    return new Response("not found", { status: 404 })
  },
}

Table changes, no code

Choose the tables; each committed change arrives on that table's channel with type change, beside the messages your function sends. Updates and deletes need the table to have a primary key.

cloudhost realtime table-changes on shop \
  --table orders --table public.items=stock \
  --events insert,update --acknowledge-always-on

Per message and connected minute

Each message written to a connected browser is one message, and each minute a connection is open is one connected minute. Presence events and pings are not counted. Table changes are billed per hour, like an always-on database. Use comes from the month's credit first, then from the wallet.

See pricing

Questions

Open your first channel

One line to publish, one WebSocket in the browser.

Sign-up is by invite for now. If you have a code, create your account.

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