The best alternatives to Shifty are Flux, Look Up for Mac, and Lumen. If these 3 options don't work for you, we've listed a few more alternatives below.
Control macOS's "Night Shift" feature directly from the command line! You can turn it on and off, pick a color temperature, and even set a daily schedule. Protect your eyes and avoid circadian-rhythm-disrupting blue light all without leaving your terminal!
Controll your mac's screen brightness based on which app is in focus. Set the desired brightness per app and continue with your work and let "menubar-auto-brightness" automatically adjust screen brightness when you switch apps. Improve your productivity!