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Install

Download the file for your computer from the download page. Every download is under 15 MB. Cold Open needs no account and no internet connection, before or after you install it.

What it runs on:

  • Windows 10 or 11, on x64 or ARM;
  • macOS 12 or later, on an Apple chip or Intel;
  • Linux on x86-64 or ARM64, with Wayland or X11, and glibc 2.35 or newer (Ubuntu 22.04, Debian 12, Fedora 36 and later).

The builds aren’t signed by Microsoft or notarized by Apple yet (why), so the first start shows a warning. Here’s what to do on each system.

Windows

  1. Run ColdOpen-…-windows-x64-setup.exe (or arm64 on Windows on ARM).
  2. If SmartScreen says “Windows protected your PC”, click More info, then Run anyway. It shows for programs that aren’t signed yet, not because something is wrong.
  3. The installer needs no administrator rights. It installs for you alone, in %LOCALAPPDATA%\Programs\Cold Open, and adds a Start menu entry.

It also:

  • puts the command-line tool coldopen on your PATH (a box you can untick). Open a new terminal to use it;
  • offers Cold Open in Open with for .fountain and .fdx files, and opens .coldopen projects. Windows lets only you choose the default app for a type: right-click a file ▸ Open with ▸ Choose another app.

Without installing: unzip ColdOpen-…-windows-x64.zip anywhere and run Cold Open.exe. coldopen.exe is beside it.

Upgrading: run the new installer. If Cold Open is open, it asks to close it first. Nothing you typed is lost: it’s all in the crash journal, and the next start brings it back.

Uninstalling: Settings ▸ Apps ▸ Cold Open ▸ Uninstall. Your scripts and settings are left alone.

macOS

  1. Open the .dmg and drag Cold Open to Applications.

  2. Open Cold Open. The first time, macOS refuses, because the app isn’t notarized.

  3. Open System Settings ▸ Privacy & Security, scroll down to the message about Cold Open, and click Open Anyway. Then open Cold Open again and confirm.

    On macOS 12 to 14 you can instead Control-click the app in Applications and choose Open.

  4. If macOS says the app is damaged, it’s the quarantine flag on an unnotarized download. Run this in Terminal, then open it again:

    xattr -dr com.apple.quarantine "/Applications/Cold Open.app"

The command-line tool: in Cold Open, open the palette (Cmd+K) and choose Install the command-line tool. It puts a coldopen link in /usr/local/bin, or in ~/.local/bin when that’s the one you can write, and says which. It never asks for your password.

A known issue: double-clicking a script in Finder starts Cold Open but doesn’t open the script yet. Use Open (Cmd+O) in the app.

Uninstalling: drag Cold Open from Applications to the Trash.

Linux

Pick one of the three packages.

.deb (Debian, Ubuntu, Mint, Pop!_OS):

sudo apt install ./cold-open_*_amd64.deb

This puts coldopen-app and coldopen in /usr/bin, with a menu entry and file types. Remove it with sudo apt remove cold-open.

AppImage (any distribution):

chmod +x ColdOpen-*-x86_64.AppImage
./ColdOpen-*-x86_64.AppImage

The command-line tool is inside: ./ColdOpen-*.AppImage cli --help, or make a link named coldopen to the AppImage. An AppImage doesn’t add a menu entry by itself; a tool such as AppImageLauncher can. To remove it, delete the file.

Flatpak (any distribution with Flatpak):

flatpak install --user ColdOpen-*-x86_64.flatpak
flatpak run io.github.theyungstump.coldopen
  • It runs on the freedesktop 25.08 runtime. If Flatpak can’t find it, add Flathub first: flatpak remote-add --user --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo.
  • The Flatpak can open scripts in your home folder. For another drive, run flatpak override --user --filesystem=/path/to/drive io.github.theyungstump.coldopen.
  • The command-line tool is flatpak run --command=coldopen io.github.theyungstump.coldopen. You can add alias coldopen='flatpak run --command=coldopen io.github.theyungstump.coldopen' to your shell’s startup file.
  • Remove it with flatpak uninstall io.github.theyungstump.coldopen.

On ARM64, the files say arm64 or aarch64 in place of amd64 and x86_64.

Check a download

Each release has SHA256SUMS.txt, which lists every file’s SHA-256 checksum. A file that matches is exactly the one the release built. Put the checksum file beside your download, then:

  • Linux: sha256sum -c SHA256SUMS.txt --ignore-missing
  • macOS: shasum -a 256 -c SHA256SUMS.txt --ignore-missing
  • Windows (PowerShell): Get-FileHash .\ColdOpen-…-setup.exe, then compare the hash it prints with that file’s line in SHA256SUMS.txt.

“OK” (or matching hashes) means the download is good. Anything else: download it again, and if it still doesn’t match, please tell us.

Where Cold Open keeps things

Uninstalling never touches these:

  • Settings (settings.json, keymap.json, flow.json): %APPDATA%\Cold Open on Windows, ~/Library/Application Support/Cold Open on macOS, ~/.config/coldopen on Linux.
  • Untitled scripts, crash reports, the usage summary and other app data: %LOCALAPPDATA%\Cold Open on Windows, the same folder as the settings on macOS, ~/.local/share/coldopen on Linux.
  • Each script’s crash journal sits beside the script while it’s open (see Recovery).