Sleepr
This simple menu bar app brings back the option to set a timer at the end of which your Mac goes into sleep mode (removed from macOS Ventura and Sonoma).
Don’t go to sleep
This menu bar app prevents your Mac from sleeping while selected applications are running.
Sleep Control Center
This menu bar app prevents your Mac from entering Sleep mode. You can control your system in terms of display, sleep, and power saving
SleepWithMe
SleepWithMe automatically puts your Mac to sleep after a certain time. Comes in handy when you’re watching a show, listening to music, or an audio book just before you go to sleep.
NoSleep
Stim
Stim prevents your Mac from going to sleep or keeps its screen from dimming. It can also keep your Mac awake only when running a specific program.
SwiftGuard
This menu bar app automatically shuts down your Mac if an unidentified USB device is plugged in. It continuously monitors USB ports for device activity, even in sleep mode
Insomniaz
This menu bar app prevents your Mac from falling asleep at all costs. It allows you to use “clam-shell” mode without hooking up a power source.
Coffee Bar
Coffee Bar prevents your Mac from going to sleep. Launch the app, click on the coffee cup icon in your menu bar, and it will keep your computer awake indefinitely.