Free and open source

Your screen, on any device with a browser

Mirror a Windows, Mac, or Linux screen to a phone, tablet, or another computer. One command on the laptop, one QR scan on the viewer. Nothing to install anywhere else.

$ npx castview

The only requirement is Node.js on the computer being shared.

$ npx castview
Castview server running
Port: 8080
Access PIN: 7231
Open one of these on your tablet/phone browser:
  http://192.168.1.42:8080   (Wi-Fi)

Scan to view: [QR code]

How it works

Three steps, under a minute

No accounts, no pairing codes to type, no cables to buy. If your phone camera can see a QR code, you're in.

Run one command

npx castview starts the server and opens a setup page with a QR code for every network you're on.

Scan with the camera

Point the phone or tablet camera at the code. The stream opens in its browser; type the PIN shown on the setup page.

Watch live

Smooth, cursor-included streaming across your local network. Nothing ever leaves it.

Features

Built for the worst day of your laptop's life

Castview assumes almost nothing works: no admin rights, no WiFi, no working display. If you have Node and a cable, you have a screen.

Works without WiFi

A USB cable and phone tethering is enough. The setup page detects the connection and shows its QR code automatically.

QR to connect

No addresses to type, no apps to find. Scan with the camera and the mirrored screen opens, already signed in.

PIN protected

Every session gets a fresh random PIN, shown only on the shared computer. Sharing on an office network stays private.

Smooth streaming

Uses ffmpeg when available for fluid HD capture with the cursor visible, and falls back to pure JavaScript when it isn't.

Local only

Frames travel over your own network and nowhere else. No accounts, no cloud, no telemetry, no tracking.

No admin rights

Runs as a normal user. No installers, no drivers, no native builds. Pure JavaScript dependencies only.

“

My laptop's display died. The machine underneath was fine. It booted, the fans spun, everything worked. I just couldn't see any of it. Every fix I found wanted me to install remote desktop software on a computer I couldn't operate, or buy a capture card I didn't have time to wait for.

So I built Castview. One command I could type blind into a terminal, and my tablet became the laptop's screen, over nothing but the USB cable that was already on my desk.

If that's the situation you're in right now: plug your phone into the laptop, turn on USB tethering, type npx castview --no-pin blind and press enter. Then open your phone's browser and try addresses like 192.168.42.x:8080, the range Android tethering usually hands out. Your screen appears. That's why this exists.

Ajith M Jose

ajithmjose.com

Give your laptop a second screen's worth of life

Free, open source, MIT licensed. Runs on what you already have.

$ npx castview