Preview a Next.js app on mobile inside VS Code

Next.js serves your app on port 3000 with `next dev`; if the port is taken it picks the next free one and prints it in the terminal.

1. Install the extension and start your server with npm run dev.
2. Open the Command Palette and run “Mobile Preview: Show”.
3. Check that the address bar shows http://localhost:3000; if your terminal printed another port, type that address instead.
4. Choose a device from the menu and edit your code.

• Server and client components render the same markup on a narrow screen: check for hydration warnings after resizing.
• Images served by next/image: check that the sizes attribute makes phones download a small version.
• Fixed headers and full-height sections: use dvh units rather than vh so the mobile browser bar does not cut content.

Mobile Preview is a layout preview in a device frame, not an emulator. Check touch behavior and browser-specific rendering on a real phone before you ship.

• The viewport meta tag is present, otherwise phones lay the page out as if it were much wider.
• Tap targets are comfortably large and not too close together.
• Nothing is hidden behind the notch or Dynamic Island: see the viewport sizes and cutouts on the devices page.

What port does Next.js use in development?

Next.js serves on port 3000 by default (http://localhost:3000). If that port is busy, the dev server usually moves to another one and prints it in the terminal.

Does Mobile Preview work with Next.js?

Yes. It works with any page that loads in a browser, and it detects a local dev server automatically. You can also type any URL in its address bar.

Does the preview reload when I save?

Yes. It reloads each time you save a file.

Is it free?

There is a free version with three iPhone models. Pro, a one-time payment of €6.99, adds Android phones, iPads and more iPhones.