How to Use an Android Tablet or Phone as a Second Monitor

Android tablets are the most overlooked second screen, mostly because the best-known apps ignore them. Apple Sidecar does not support Android at all, and OpenDisplay's official apps are Apple-only. That leaves two realistic free choices, and which one you can use is decided by your main computer.

Which app can you actually use

If you are on a Mac, spacedesk is not an option; it has no Mac sender. If you are on Windows, spacedesk is the more established of the two, and BetterCast's Windows sending is still beta.

Using BetterCast

Free and open source under GPLv3, with no account required.

1. Install BetterCast on your Mac, or use the Windows beta installer, which includes the virtual display driver it needs.
2. Install the BetterCast receiver on the Android tablet or phone from the official release download.
3. Open both apps and join the same local network. Allow local-network access when prompted.
4. On a Mac, allow Screen Recording so BetterCast can capture the display. Accessibility permission enables input from the tablet back to the computer.
5. Select the Android device in BetterCast and connect. There is also a wired option over USB using ADB.
6. Arrange the new display on the sending computer and set it to extend rather than mirror.

You can connect more than one receiver at once, and each gets its own virtual display and resolution, so an Android tablet and a phone can both be active at the same time.

Using spacedesk

spacedesk has been around for years and is free for personal use, with Android, iOS and browser clients. Install the driver on the Windows PC and the viewer app on the tablet, then pick the PC from the list.

Two limits worth knowing before you start: the host must be Windows, so a Mac or Linux machine cannot send to it at all, and commercial use requires a paid licence.

Wireless or USB?

Wireless is easier and needs no cable, but every wireless screen stream depends on the network it runs over. A congested 2.4GHz band, a busy access point, or a guest network that isolates devices will all cause problems that look like app bugs.

A USB connection avoids the network entirely, which is worth trying if wireless is unreliable. BetterCast supports a wired Android connection over ADB.

If wireless is your only option, prefer 5GHz, stay near the router, and check that the network does not isolate clients from one another.

Why is my tablet not appearing?

Keep the receiver app open and in the foreground. Confirm both devices are on the same network and that local-network permission was granted. Guest and public networks frequently block devices from seeing each other even when the name is identical. Check whether a VPN or firewall is blocking discovery, and allow the app rather than disabling the firewall. On a Mac, a black screen almost always means Screen Recording permission is missing; grant it and restart the app.

Does this work with a Linux computer?

Not as the sender. BetterCast does not extend a Linux desktop; Linux is supported as a receiver only, so a Linux machine can act as the extra screen for a Mac or Windows sender. See the Linux guide. For extending a Linux desktop itself, Deskreen is the option to look at.

Sources and review

This is a BetterCast product guide, not an independent review. Platform roles were checked on September 7, 2026 against the BetterCast README and releases and against spacedesk's official site. Features and licence terms change, so confirm current details before relying on them.

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