> ## Documentation Index
> Fetch the complete documentation index at: https://upstash.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Deployment

<Note>
  Deploy Upstash Realtime to providers that bill **based on active CPU time**. Great places to
  deploy are

  * Vercel with Fluid Compute enabled
  * Cloudflare
  * Railway
  * A personal VPS
  * any other service that does not bill based on connection duration.
</Note>

## Deploying to Vercel

To deploy Upstash Realtime to Vercel, [enable Fluid Compute](https://vercel.com/docs/fluid-compute#enable-for-entire-project) for your project. For new projects, this is enabled by default.

Fluid Compute allows for less cold-starts, has much higher function timeouts compared to serverless functions, and most importantly **only bills for active CPU time**.

That way, you're only billed for actual message processing time, not connection duration.

<Frame>
  <img src="https://mintcdn.com/upstash/IhGKcftpCFCMbFa7/img/realtime/vercel-fluid-enabled.png?fit=max&auto=format&n=IhGKcftpCFCMbFa7&q=85&s=8e435be20d9e2df4a8614a298e1d9045" width="1585" height="876" data-path="img/realtime/vercel-fluid-enabled.png" />
</Frame>

## Optional: Configure Max Duration

You can configure the maximum duration for your realtime connections:

```typescript lib/realtime.ts theme={"system"}
import { Realtime } from "@upstash/realtime"
import { redis } from "./redis"

export const realtime = new Realtime({
  schema,
  redis,
  maxDurationSecs: 300,
})
```

The default is 300 seconds (5 minutes), which works well with Vercel's Fluid Compute. After this interval, the client will automatically reconnect. Redis auto-replays all messages sent during reconnect.

## Billing Example

Traditional serverless connection billing:

```plaintext Serverless Billing theme={"system"}
Connection duration: 5 minutes
Billing: 5 minutes = $$$
```

Upstash Realtime with fluid compute:

```plaintext Fluid Compute Billing theme={"system"}
Connection duration: 5 minutes
Active processing: 2 seconds
Billing: 2 seconds x CPU cost = $
```

## Automatic Reconnection

The client automatically reconnects before your function timeout:

```tsx page.tsx theme={"system"}
"use client"

import { useRealtime } from "@/lib/realtime-client"

export default function Component() {
  const { status } = useRealtime({
    events: ["notification.alert"],
    onData({ event, data, channel }) {},
  })

  return <p>Status: {status}</p>
}
```

## Message Delivery Guarantee

Upstash Realtime is powered by Redis Streams, so no message is ever delivered twice or gets lost. Every message is guaranteed to be delivered exactly once.

1. Client establishes connection and subscribes to stream
2. Client initiates reconnection before function timeout (default every 5 mins)
3. Redis auto-replays all messages sent during reconnect