Install

The host needs SpecDeck, and so does every viewer who wants the app. Download it from the latest release, or use a package manager.

Can’t install? Watch in your browser

Viewers who cannot install apps, for example on a company laptop, can watch in a browser instead: open the host’s link, or the sharing service’s address, in current Chrome, Edge, Firefox or Safari. Hosting needs the app.

Platform	How
macOS 11 or later (Apple silicon)	brew install --cask nickhartjes/tap/specdeck, or SpecDeck-arm64.dmg
macOS 11 or later (Intel)	brew install --cask nickhartjes/tap/specdeck, or SpecDeck-x64.dmg
Windows	SpecDeck-x64-setup.exe
Linux	SpecDeck-x86_64.AppImage, SpecDeck-amd64.deb, Nix, or from source

The release files keep the same names from version to version, so a link such as https://github.com/nickhartjes/specdeck/releases/latest/download/SpecDeck-arm64.dmg always gets the newest one.

The first launch

Releases are not signed yet, so your system warns the first time you open SpecDeck:

• macOS: allow SpecDeck once under System Settings › Privacy & Security (Open Anyway), or run xattr -dr com.apple.quarantine /Applications/SpecDeck.app. The Homebrew cask says the same when it installs.
• Windows: choose More info › Run anyway in the SmartScreen prompt.

On macOS, the first time you host or join, macOS also asks whether SpecDeck may find and connect to devices on your local network. Select Allow: SpecDeck connects directly to teammates on the same network when it can.

Installing also registers specdeck:// links, so clicking a join link opens SpecDeck.

Nix

The flake builds SpecDeck from source, for x86_64 and aarch64 Linux:

nix run github:nickhartjes/specdeck

To add it to a NixOS or Home Manager configuration, use the flake’s packages.<system>.specdeck or overlays.default.

The Nix package uses the public sharing service, wss://specdeck.hartj.es/signal, like the release builds. To use your team’s own service, override it:

specdeck.override { signallingUrl = "wss://specdeck.example.com/signal"; }

Or set the service in Settings, which works for every install.

From source (Debian, Ubuntu and WSL)

When the release files cannot be used, for example on a work laptop that blocks installers, build SpecDeck from source with one script. On Windows this works in Ubuntu under WSL 2: the SpecDeck window opens on the Windows desktop. Check first that your organisation allows running software in WSL.

git clone https://github.com/nickhartjes/specdeck.git ~/specdeck
~/specdeck/scripts/install-from-source.sh

The script asks for your sudo password once to install the system libraries, installs Rust, Node and the other build tools for your user only with mise, and builds the app with the public sharing service, like the release builds. The first build takes several minutes.

Then start SpecDeck with specdeck, or from the application menu. specdeck keeps the terminal attached, with the app’s output there, until you close the window or press Ctrl+C; specdeck --background frees the terminal and logs to ~/.cache/specdeck.log. In WSL it also appears in the Windows Start menu under Ubuntu, and wsl -- bash -lc specdeck starts it from PowerShell.

• Coding agents run inside Linux: install the agent (Claude Code, Codex, …) in Ubuntu as well; the Windows one is not used.
• Update: run git -C ~/specdeck pull and the script again. A build from source does not update itself.
• Your team’s own sharing service: set it in Settings, or build it in with SPECDECK_SIGNALLING_URL=wss://specdeck.example.com/signal ~/specdeck/scripts/install-from-source.sh.

Update

From version 1.2.0, SpecDeck updates itself when it was installed from the .dmg, with Homebrew, with the Windows installer, or as the AppImage. It checks for a new release when it starts and every 6 hours, downloads it in the background, and then shows SpecDeck 1.2.1 is ready (with the new version) and Restart to update. Nothing is installed until you choose that, and SpecDeck never restarts by itself. Sessions you host keep running through the restart, with your viewers connected, and open again in their windows afterwards; versions before 1.7.0 end them. While you watch a session, SpecDeck asks first, because restarting leaves it; you can join again with the invite code.

• Check now: SpecDeck › Check for Updates… on macOS, Help › Check for Updates… on Windows and Linux.
• Turn the background checks off: Check for updates automatically in Settings. Check for Updates… still works.
• Versions before 1.2.0 cannot update themselves: install 1.2.0 by hand once, as below.
• Only final releases are offered, never test releases, and every update is checked against SpecDeck’s signature before it is installed. A check only asks GitHub for the newest release; it sends nothing about you or your sessions.
• macOS asks again for Local Network access after each update, because releases are not signed with an Apple Developer ID yet. Select Allow again.

Where SpecDeck does not update itself:

• .deb: download the new release and install it over the old one. Your settings stay.
• Nix: update the flake input.
• From source: pull and run scripts/install-from-source.sh again.
• Homebrew leaves SpecDeck to update itself; brew upgrade --greedy --cask specdeck updates it through Homebrew instead.

When the host’s and a viewer’s versions cannot work together, SpecDeck says Update SpecDeck to join or The host needs to update.