Amphetamine

Amphetamine stops your Mac from sleeping, dimming, or starting the screen saver for as long as you want. Start a quick session from the menu bar, or set up Triggers that keep the Mac awake automatically under conditions you define.

Why it makes the list

The built-in prevent-sleep options are blunt. Amphetamine is the powerful, genuinely free version: session timers, indefinite sessions, and a rich Triggers engine — stay awake while a specific app runs, while a drive is mounted, while on a particular Wi-Fi network, while the battery is above a threshold.

Standout features

• Triggers based on running apps, network, connected displays, drives, IP address, or battery level

• Timed or indefinite sessions with a one-click menu-bar control

• Allow display sleep while keeping the system awake

• Closed-display operation without external power or peripherals

• AppleScript support for scripted control

Pricing

Completely free on the Mac App Store, with no ads and no in-app purchases.