Install the desktop app

The app finds your speakers and hands them the audio. You install it once.

It is not signed yet, so Windows and macOS ask before they open it. Signing is planned. Until then, this page says exactly what to click, and the download page shows the same steps, with drawings, after you click Download.

Windows

1. Download the installer.

   From the download page: the Windows installer (.exe), for Windows 10 or 11, 64-bit. Managing several computers? There is an .msi too, under all files.

   If your browser says the file is not commonly downloaded, choose Keep: that is the same missing signature.

2. Get past “Windows protected your PC”.

   Windows shows this for apps it does not know yet, and an unsigned app like this one is one of them. Select More info, check that the app named is the file you just downloaded (“Unknown publisher” is the unsigned part), then select Run anyway.

3. Allow it on private networks.

   When Windows asks whether the app may use the network, allow Private networks. Your speakers fetch the audio from this computer, on ports 49400 to 49410, so they need to be let in. More on that in Firewall and ports.

4. Finish the first-run tour.

   The app looks for your speakers and counts the rooms that answered. Turn on Launch at login, so it is already running when you want to cast. You can change it later in Settings.

Windows says Smart App Control blocked it?

On Windows 11, Smart App Control blocks unsigned apps it does not recognise, and there is no way past it for one app. Recent versions of Windows let you switch it off and on again in Windows Security, but that covers every app. Until Thaumic Cast is signed, run the app on another computer on your network (a Mac, another PC, or Thaumic Cast Server on Linux) and enter its address in the extension’s Settings.

macOS

1. Download it and drag it into Applications.

   From the download page, get the .dmg for your Mac: Apple silicon or Intel. Not sure which? Apple menu, About This Mac: “Chip” means Apple silicon, “Processor” means Intel. Open the .dmg and drag Thaumic Cast onto the Applications folder. It needs macOS 13 or later.

2. Open it, then select Done.

   macOS says Thaumic Cast was “Not Opened”, because it cannot check an app that is not signed. Select Done, not Move to Trash. On macOS 13 and 14 the message is worded differently and the button says OK.

3. System Settings › Privacy & Security › Open Anyway.

   Scroll down to Security. Where it says Thaumic Cast was blocked, select Open Anyway. The button stays there for about an hour.

4. Confirm, then allow the local network.

   macOS asks once more: choose Open Anyway and enter your password. On macOS 15 and later it then asks whether Thaumic Cast may find devices on your local network. Allow it: that is how it finds your speakers.

5. Finish the first-run tour.

   Turn on Launch at login if you would like it running whenever you want to cast. You can change it later in Settings.

Control-click and Open no longer works

On macOS 15 and later, Control-click and Open does not get an unsigned app past Gatekeeper. On every version, Open Anyway in Privacy & Security is the way through.

Linux

1. Install the package.

   Get the file for your system from the download page, then, in the folder you saved it to:

   • Debian-based systems (.deb): sudo apt install ./Thaumic.Cast_*_amd64.deb
   • Fedora (.rpm): sudo dnf install ./Thaumic.Cast-*.x86_64.rpm
   • AppImage, for anything else: it needs FUSE 2 first, sudo apt install libfuse2 (libfuse2t64 on Ubuntu 24.04). Then make the file executable and run it.

   The Linux builds are x64 only. On a computer with no screen, run Thaumic Cast Server instead: Run Thaumic Cast Server.

2. Open the ports.

   If a firewall is on, allow 49400 to 49410/tcp from your network; nothing will prompt you. The commands are in Firewall and ports.

3. Finish the first-run tour.

   Turn on Launch at login if you would like it running whenever you want to cast. You can change it later in Settings.

Check it worked

The last step of the tour says Ready to cast, with Desktop app: running and Rooms: followed by how many answered. No rooms answered? See No speakers found.

Why the warning?

Signing an app costs money every year, and this one is free. Signing is planned. Until then, every file’s SHA-256 checksum is on the security page, so you can check your copy is the one we published.

Next

Add the extension and cast your first tab. The app lives in the tray or menu bar from then on: The desktop app says what is in it.