[KevinH]

This is Apple's new GateKeeper in Action. First check your Apple Settings and select Security & Privacy and then the General tab. Under it check Allow apps downloaded from AppStore and identified developers.

Then once you have that set, you should be able to do the following:

1. download the Mac *.txz file from our Releases Page
2. Drag it out of Downloads onto your Desktop
3. Double-click to unpack it and it will show the Sigil.app
4. Move that Sigil.app to /Applications
5. In /Applications right click on the Sigil.app and in the pop-up menu select "Open"
macOS will post its fear raising warning
6. Immediately afterwards use the right click to show the pop-up menu and select "Open" once again

This should then validate the code against my digital signature and you should not be bothered again.

Please note for many graphical plugins to work you should download and install the ActiveState's Active TCL version 8.6.X (the latest 8.6 version). This will enable the plugin Tk graphics as the version that comes pre.installed on macOS is much much too old to be useful.

Just ask if you have any questions.

KevinH