5 Best Free Second Monitor Apps for Mac, Windows & Linux (2026)
Looking for a free second monitor app? Here are the 5 best free options to turn your tablet, phone, or spare laptop into an extra display in 2026.
You don't need to spend money to get a second monitor. Several free apps can turn your existing tablet, phone, or spare laptop into a functional second display. Here are the five best free options available in 2026.
1. BetterCast — Best Overall Free Option
Platforms: macOS, Windows, Linux (host) | iOS, Android (client)
BetterCast is a free, open-source second display application that stands out for its cross-platform support and performance.
Why it's #1:
- Works across all major operating systems — including Linux
- Ultra-low 0.02ms latency with 60 FPS at 4K
- No account required, no internet needed
- Peer-to-peer connection over your local network
- Just 3MB install size
- Fully open source (GPL 3.0)
BetterCast is ideal for developers, remote workers, and anyone who wants a no-strings-attached second monitor solution.
2. Apple Sidecar — Best for Apple Users
Platforms: macOS + iPadOS only
Sidecar is Apple's built-in solution for using an iPad as a second Mac display. It's seamlessly integrated into macOS and works over USB or wirelessly.
Why it's great:
- Zero setup — works out of the box
- Native Apple Pencil support
- Excellent performance over USB
- No additional software to install
Limitations: Apple ecosystem only. No Windows, Linux, or Android support. Requires hardware from 2016 or later.
3. Spacedesk — Best for Windows Users
Platforms: Windows (host) | iOS, Android, Windows, web browser (client)
Spacedesk is free for personal and academic use and supports up to three simultaneous client displays.
Why it's great:
- Supports multiple screens at once
- Works with any device that has a web browser
- Audio redirection support
- KVM functionality
Limitations: Windows-only as the host machine. Commercial use requires a paid license.
4. Deskreen — Best for Browser-Based Clients
Platforms: macOS, Windows, Linux (host) | any web browser (client)
Deskreen is an open-source app that streams your desktop to any device with a web browser using WebRTC.
Why it's great:
- Works with literally any device that has a browser
- Multi-device simultaneous connections
- End-to-end encryption
- Cross-platform host support
Limitations: Requires a Virtual Display Adapter dongle for true extended desktop (otherwise limited to screen mirroring or single-app sharing). Higher latency than native solutions due to WebRTC overhead.
5. VirtScreen — Best for Linux Power Users
Platforms: Linux only
VirtScreen creates a virtual screen on Linux and streams it to any VNC client. It's a lightweight, open-source option for Linux users.
Why it's great:
- Native Linux solution
- Uses standard VNC protocol
- Lightweight and minimal
Limitations: Linux-only, requires some technical setup, no native mobile clients (use any VNC viewer app).
Quick Comparison
| App | macOS | Windows | Linux | iOS | Android | Account Needed |
|---|---|---|---|---|---|---|
| BetterCast | Yes | Yes | Yes | Yes | Yes | No |
| Sidecar | Yes | No | No | Yes | No | Apple ID |
| Spacedesk | No | Yes | No | Yes | Yes | No |
| Deskreen | Yes | Yes | Yes | Browser | Browser | No |
| VirtScreen | No | No | Yes | VNC | VNC | No |
Which Should You Pick?
- Want the most versatile free option? Go with BetterCast — it covers every platform
- All-Apple setup? Sidecar is unbeatable for simplicity
- Windows-only? Spacedesk gives you multi-display support for free
- Need browser-based streaming? Deskreen works with anything that has a browser
- Linux enthusiast? BetterCast or VirtScreen are your best bets
The days of needing to pay for a second monitor app are over. All five of these options are genuinely free and capable of transforming your productivity setup.
Ready to try BetterCast?
Free, open-source, and works on every platform. Turn any device into a second monitor in under a minute.