Night Shift and f.lux (free) sound identical at a glance. They both attempt to reduce your exposure to blue light at night by applying a warmer color filter to your screen after the sun goes down. The similarities between the two end there though, and in typical Apple fashion, which one you use depends primarily on how much you like to tinker with settings.
F.lux Offers Way More Options to Tweak How It Works
The biggest and most important difference between f.lux and Night Shift comes in the form of your options for customization. With Night Shift, you can set when Night Shift activates, and then choose a color temperature on a scale of Less Warm to More Warm.
F.lux offers a somewhat insane variety of options. You can choose the temperature of your screen during the day, at sunset/sunrise, and at bedtime. You can choose from various color presets or create your own. There’s even a Night Owl setting for those who actually prefer to work late into the evening.
Beyond that, f.lux also allows you to set how long the transitions between colors last, what time you get up on the weekend, and you can set reminders when it’s getting close to your bed time. F.lux even includes several specific types of color effects, like a dark room mode that inverts colors, a movie mode that preserves colors while reducing certain lights, and a mode that automatically triggers the macOS dark theme at sunset.
Night Shift’s Effect Is Less Noticeable
Since it’s shipping with a commercial product, Night Shift is also a little less extreme than f.lux. This isn’t necessarily a bad thing, Night Shift is targeting a broad set of people, whereas f.lux is filling a niche. F.lux breaks down the differences in a forum post, the main difference being in how f.lux also reduces blue-green light:
F.lux claims that Night Shift just doesn’t reduce enough light to help with sleep. We know that the supposed effect here is about much more than just reducing the blues, but it’s hard to say whether one or the other is actually better for sleep.
Regardless, Night Shift is much less intrusive because all it does is add a warmer filter to your display, and you can use it without disrupting your general computer usage that much, unless you’re working on color correction in photos or videos. Even with all of the different settings tweaks you can do, f.lux has a much more noticeable impact because it does more than just apply a warmer filter; it changes the overall amount of light alongside the color.