The installer download should start automatically in a few seconds.
Opening the installer may bring up a blue SmartScreen notice. Nothing clever is needed: the way through is inside the notice itself.
Vixnap is signed with an Azure Trusted Signing certificate, and you can check it in Properties → Digital Signatures. What the certificate lacks is reputation, and reputation is earned through real downloads: the notice will go away on its own.
It installs into your own user account, with no administrator rights. Vixnap sits in the system tray and opens no window.
The screen freezes and everything happens inside the overlay: you pick the area, annotate, copy or save. Once you confirm, Vixnap disappears.
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