Amphetamine is a free keep-awake app created for macOS.
Amphetamine can keep your Mac, and optionally its display(s), awake through a super simple on/off switch or automatically through easy-to-configure Triggers. Amphetamine is potent and includes advanced features for those who need them yet remains intuitive and easy to use for those who don't need all of the bells and whistles.
Quickly start a keep-awake session from Amphetamine's menu to keep your Mac awake.
Indefinitely, for a specified amount of time, or until a specified time
While a file is downloading
While a specific app is running
During a keep-awake session, choose to allow or prevent: