Share a Vite dev server

Open your Vite dev server from a phone or a teammate's laptop, with an HTTPS URL that reaches your machine.

Before you beginCopy Anchor Link

• Node.js 18 or later
• A Horizon account and the CLI (see Getting started)
• A reserved subdomain for -s. Reserve one on the Subdomains page.
• A Vite project

npm run dev

hrzn tunnel http://localhost:5173 -s my-app

HORIZON: Tunnel connected
  URL          https://my-app.hrzn.run (reserved)
  Forwarding   http://localhost:5173
  Request log  https://hrzn.run/dashboard/tunnels/my-app

Check it worksCopy Anchor Link

The page loads and the Horizon terminal prints a line per request:

  GET     200  /

Edit a source file and save. The page updates without a reload.

Why you don't need allowedHostsCopy Anchor Link

Vite checks the Host header of every request. It allows localhost, domains under .localhost and all IP addresses by default. Horizon sets Host to localhost:5173, so Vite sees an allowed host. The public hostname arrives in X-Forwarded-Host, which Vite doesn't check.

Tested against Vite 8.3.4: a request with Host: my-app.hrzn.run got a 403, and a request with Host: localhost:5173 and Origin: https://my-app.hrzn.run got a 200 for a module file.

Hot module replacementCopy Anchor Link

Vite serves hot module replacement (HMR) over a WebSocket on the same port, and the tunnel passes WebSockets through. If the browser console shows a failed WebSocket connection, set the client side of that connection with server.ws. Vite documents clientPort as the option to "override the port on the client side".

import { defineConfig } from "vite";

export default defineConfig({
  server: {
    ws: {
      protocol: "wss",
      clientPort: 443,
    },
  },
});

Add this only if HMR fails. Most setups don't need it.

TroubleshootingCopy Anchor Link

Blocked request. This host ("my-app.hrzn.run") is not allowed.Copy Anchor Link

Vite prints Blocked request. This host ("my-app.hrzn.run") is not allowed. To allow this host, add "my-app.hrzn.run" to server.allowedHosts in vite.config.js. Something sent your public hostname as Host. That means a proxy sits between the tunnel and Vite, or you tunneled to a URL that isn't localhost. Point the tunnel at http://localhost:5173. If you can't, add the hostname:

import { defineConfig } from "vite";

export default defineConfig({
  server: {
    allowedHosts: ["my-app.hrzn.run"],
  },
});

Vite warns that allowedHosts: true lets any website send requests to your dev server and download your source code. Use a list.

Port 5173 is in use, trying another one...Copy Anchor Link

Vite moved to the next free port, so your tunnel points at the wrong one. Read the Local: line Vite prints and tunnel to that port, or free port 5173.

The URL changed after a restartCopy Anchor Link

You started the tunnel without -s, so Horizon gave you a new random subdomain. Restart with -s my-app.

Next stepsCopy Anchor Link

• Read Vite's server options.