OpenCalc on your desktop.

Your computer will stop you once. Here is why, and what to do.

Signing an application means paying Apple or a certificate authority to vouch for it. This project has not done that yet, so each operating system treats these builds as being from an unknown source. That is a fair thing for them to do — and it means you should only ever run this step on a file you downloaded from the link above, having checked it against the published checksum if you want to be careful.

macOS — two different messages, two different fixes

macOS shows one of two dialogs, and they are not the same problem. Read which one you got before running anything.

“Apple could not verify OpenCalc is free of malware.” This is the ordinary unsigned-application block. Clearing the “downloaded from the internet” flag is the whole fix:

xattr -dr com.apple.quarantine /Applications/OpenCalc.app

On macOS 15 and later the old right-click → Open trick no longer works; if you would rather not use Terminal, open System Settings → Privacy & Security, scroll to the message about OpenCalc, and click Open Anyway.

macOS — “OpenCalc is damaged and can’t be opened”

It is not damaged. That is the wording macOS uses when it cannot validate a signature, and it is the same message you would get for a genuinely corrupt file — which is why it is worth being explicit about. Drag OpenCalc to your Applications folder, then run these two lines in Terminal:

xattr -dr com.apple.quarantine /Applications/OpenCalc.app

0.0.0 also needed a second line, because its bundle carried a signature from the linker that sealed no contents and macOS rejects a bundle whose signature does not describe what is inside it. 0.0.1 signs at build time, so clearing the quarantine flag is all that is left. If you are still on 0.0.0, run codesign --force --deep --sign - /Applications/OpenCalc.app as well — or just download 0.0.1.

Apple Silicon only. The 0.0.0 .dmg is built for arm64 and will not run on an Intel Mac. If you are on an Intel Mac, use the web editor for now — it is the same engine.

Windows — “Windows protected your PC”

SmartScreen hides the button by default. Click More info, then Run anyway. There is no command to run and nothing to change in your settings.

Linux — the AppImage is the one that works everywhere

It needs the executable bit before it will run. Double-clicking a file without it does nothing at all, with no message — which is the most common reason this appears not to have downloaded properly.

chmod +x OpenCalc_0.0.3_amd64.AppImage
./OpenCalc_0.0.3_amd64.AppImage

If it still does nothing, you are missing FUSE 2. AppImages mount themselves with it, Ubuntu 24.04 ships only FUSE 3, and the failure is silent. Either install it once, or skip it entirely — the second line needs nothing installed:

sudo apt install libfuse2t64      # Ubuntu 24.04
sudo apt install libfuse2         # Ubuntu 22.04

./OpenCalc_0.0.3_amd64.AppImage --appimage-extract-and-run   # or no install at all

The .deb needs Ubuntu 23.04 or later

It declares libwebkit2gtk-4.1-0, and that package does not exist before Ubuntu 23.04 — 22.04 LTS has 4.0. On 22.04 the install fails outright with an unmet dependency, which is a limitation of this build and not something you can configure around.

Use the AppImage there. It carries its own copy of webkit2gtk and GTK — that is what the ~89 MB is — so it does not use the system's at all.

sudo dpkg -i OpenCalc_0.0.3_amd64.deb    # Ubuntu 23.04+
sudo apt -f install                      # if it reports missing dependencies

Checking what you downloaded

Nothing here is signed, so a checksum is the only thing you can actually verify. Download SHA256SUMS.txt into the same folder and run:

shasum -a 256 -c SHA256SUMS.txt --ignore-missing