Sundown is a small panel in the menu bar with a warmth slider, presets and an on and off switch, so you can make your Mac's screen warmer and dimmer in a click instead of going through System Settings. The warmth runs from the normal 6500 K down to a deep red at 500 K in 100 K steps, and a custom schedule can change it for you through the evening.
It runs on macOS 14 and later, on Apple Silicon and Intel, and there is a Classic build for macOS 12 Monterey and macOS 13 Ventura. It's made by Jack Richards.
The site also has a free Blue Light Calculator, and Screen flicker and eye strain research collects the published studies and says plainly where the evidence is thin. More about the app is on Sundown.
