Best alternative to f.lux

F.lux is a popular blue light filter program, but I personally hated several things about this program.

When I started to have eye problems in 2015 I wanted to be able to manually control the blue light of my screen. I found f.lux while reading one article about how to feel less eye strain, but what I didn’t like about it was that it was somehow focused on sleep which was not my problem.

I had awesome sleep, but I was feeling really bad eye strain when I used computers. I wrote to the dev team if they can add custom control of the blue light and schedule by time, but they didn’t respond to me.

And this is how I decided to add blue light and color temperature to Iris.

In this article, I want to make a general comparison between the 2 programs, but take my words with a little grain of salt since I’m a little tendentious πŸ˜€

What f.lux is missing?

Let’s first start with f.lux 3 which was somehow the first version of f.lux and was actually better than the new f.lux 4 beta which is bloated with not needed features.


The f.lux app main assumption is that blue light is bad for your sleep. Not exactly bad, but we are made to have day and night cycle of light and at night you should lower blue light to sleep better.

This is good. This is true. Melatonin secretion stops when our eye sees blue light.

But do people problem is actually bad sleep or it is eye pain?

Sleep vs Eye pain

I and 99% of all other people who use blue light reduction software use it because we feel less eye strain when we remove the blue light from our screen at night.

So I don’t actually need this day and night cycle of the Sun thing. I don’t actually need to sleep better.

I train a lot, eat good and even with a cup of coffee before bed I sleep well. What my problem really is is that I feel a lot of eye pain from my constant work in front of computer screens.

This is a fundamental problem. I don’t need all of this day and night graphics of how light affects my sleep and what value is best to sleep better.

I just want 1 slider with 0% and 100% blue light.

That’s it. I want to set the blue light to my comfortable value and maybe automate this based on the time of the day.

It’s not only the melatonin suppression effect. It’s the strong wavelengthΒ of blue light which enters deep into our retina causes eye strain and macular degeneration in the long run.

Color temperature vs Blue light

And what is this color temperature anyway?

Most people are not familiar with the black body color and this color temperature thing only makes them more confused.

In the past, people often asked me What is the best Color temperature?.

At one point I just realized that this whole color temperature scale thing is broken and it will actually be better to have a blue light slider fromΒ 0 to 100%.

After some time it becomes comfortable to work with the color temperature values but why waste your time learning science.

Sun vs Time

For me, it’s quite unclear why you are locked for only selecting the time and to base day and night calculations only on Sun position.

This is quite helpful when you want more precise control of the lighting outside but combined with strange geographic locations it may give wrong values at the wrong time.

Also, f.lux can’t automatically detect your location without using Geolocation which brings me to the next point.

Geolocation vs Approximation

Software like f.lux can easily detect location with only internet request by approximation which is what Iris does.

Geolocation uses a lot of battery and can be used to track users positions which is also not good in terms of privacy.

If something is free you are the product of sale. Why Facebook and Google are free?

Because they both track your every move and advertise based on your activity. I don’t want to tell anything bad, but free software often sell user data to make money.

Free vs Paid

Free software is great because it’s free but you often don’t have any customer support. Since you almost can’t make a living from donations you work a side job and you don’t care much about the product.

In the beginning, I also made Iris free, but after a year full-time work and 0$ donations, I decided to make it Freemium with Pro version.

The reason why f.lux make so little changes and listen to users so little is because it’s free. Free software with good customer support sell ads or user data.

I personally hate programs with ads and tracking users is just unethical and plain evil. Totally free and open source programs don’t have any support for bugs and problems.

This is the reason why I think freemium or paid software is actually much better.

Locked values

One of the things I hated when I started using f.lux is that I was unable to go lower than 2700K during the day. 1200K and other values were available only during the night.

But what if you are in a really dark room during the day. Or you are even going to be night shift and you want to shift your sleep times.

You need to open Google maps and find a location with some close latitude and longitude to the timezone you desire. It was just crazy.

PWM flicker

For eye pain and eye problems, blue light is actually not the biggest problem.

Screen illumination, PWM flicker, and generally bright screens are a much bigger problem for our eyes.

F.lux doesn’t include a solution for PWM flicker and this is one of the reasons why Iris is much better. Iris has an automatic brightness reduction without flicker based on time or location in combination with a blue light reduction.

Room lighting

Screen brightness should match the room lighting and the monitor should not look like a light source in the room. Otherwise, our eye starts to move like this

This is a bigger amplitude to show the effect of course but the idea is simple.

Your monitor should not actually adapt to the Sunlight but to the light around you and the light in your room. You can achieve this with light detection from the camera or from the easy manual control of the brightness.

Both ways are not part of f.lux and are part of Iris. Camera detection is disabled by default because it’s creepy some software to use your camera, but you can enable it from the AI pageΒ of Iris.

Eye rest

One of the most underestimated things for eye health is to take regular breaks and look at distant objects.

F.lux doesn’t include a solution for this while Iris has several different timer modes based on strictness and customizable timing.

One of the most popular ophthalmologist health advice is the 20-20-20 rule which goes like this:

Every 20 minutes, take a 20-second break and focus your eyes on something at least 20 feet away.

Rest is important for moisturizing our eyes and for general eye strain relief.


Most modern font rendering technologies are bad for the eyes. Here I talk about font smoothing which makes the fonts blurry.

Our eye moves in patterns called cascades and we need sharp edges to focus easily.

When font smoothing is used the letters became blurred and we struggle to find a focus point on the screen.

This may cause eye pain and headaches in the beginning and in the long run, you may need to put even glasses.

You can’t change font smoothing with f.lux.

With Iris, you can choose between different font rendering techniques and find what is comfortable for you from the Fonts page.

Easy to use user interface

Here is a picture from the old f.lux version 3:

And here is a picture from the new f.lux 4:

I know that the first versions of Iris were actually worse with 25 pages of settings, but after a lot of talking with users we packaged it in presets and it’s really intuitive.

In 2017 we made also one feature which a lot of people asked for and this was the presets of Iris. After some time something similar also appeared in the new version of f.lux.


Moon cycles affect our sleep as much as blue light and this is another thing that the f.lux team didn’t take into account.

It’s not only the melatonin blocking from blue light. The moon moves entire oceans and our sleep time moves when the moon moves.

If you want to read more about the moon’s influence on our circadian rhythms you can read this and similar researches. Here is a quote from the text:

“Lunar rhythms are not as evident as circadian rhythms and are thus not easy to document but they exist.Β Our findings of a 20Β min shorter sleep duration, a 5Β min longer time to fall asleep, and a 30% decrease in deep sleep are not small changes. ”

Iris is the only solution in the world right now which takes moon phases into account and regulates the blue light also based on the moon phase.

This regulation is even customizable from the Moon page in Iris Pro.

Blue light reduction during the day

f.lux doesn’t have any blue light reduction during the day which is also bad.

Doctors recommend actually using low blue light or 1200K the whole day and spending time outside to get full-spectrum sunlight.

As you can see from the picture above the Sunlight is really different from the light emitted from our electronic devices and LED screens to emit too much blue light all the time.

This is why some blue light reduction is needed even during the day.

f.lux doesn’t make any reduction during the day.

Iris Types have blue light reduction also during the day.


Shortcuts are one more thing f.lux falls short on. While in version 3 you don’t have any way to customize or disable the shortcuts the good thing in version 4 is that at least you can disable them.

With Iris, you can customize the keys of all shortcuts and most features from the Shortcuts page.

Color pausers

While there is some part solution in the f.lux newest version in f.lux version 3 which in my opinion was actually simpler there was no way to pause and disable f.lux while certain programs like Photoshop are running.

This is useful for designers and artists who need exact colors when they work with colors or paint something.

In f.lux 3 there is no solution to this problem. In the newest f.lux 4, there is a big improvement and you can select your latest programs from the tray menu

The problem is that this is not the best user-friendly design and also some people want to create a list of programs without the need to start the program to remove it from the list.

Iris has both these features available from the tray menu and from the main user interface.

Iris also gives you the ability to add your own custom programs from a list.

Part screen blue light reduction

While the color pausers feature is useful, sometimes part screen blue light reduction is needed for long periods of work with colors.

With f.lux you don’t have any solution for this while with Iris you can select a part of the screen to be with normal colors and the other part of the screen to be with reduced blue light.


Looking at small texts can be straining for the eyes and magnification is yet another area in which f.lux doesn’t have any solution.

Some programs have automatic zoom, but I like this example when on YouTube there are some videos that are displayed on only half of the screen. Even on fullscreen, the subtitles are small. Example

With Iris, you can magnify the screen and watch it like this

You can see the shortcuts to Zoom in and Zoom out from the Magnification page.

Color schemes

Some people want to remove only blue light without removing the green color and this is one more area in which you can’t find a solution in f.lux.

F.lux removes the green light from 6500K downwards. One of the reasons for this is that they wrongly use the color temperature scale to reduce the blue light.

The good thing about this is that the green pixel in modern monitors actually emits also blue light but I’m not sure if they have measured this much this.

Some people just don’t want to remove the green light when they decrease blue light and with Iris color schemes you can do this.

From the Color schemes page, you can select different color schemes.

Some of them like Magmus is more aggressive while Olaf is an exact match of the f.lux color scheme.

Iris color scheme is the measured best which most people like and is a combination of the best from every scheme but what we are interested in here is the Groot color scheme.

Groot removes only blue light without touching the green light all the way down to 0% blue light from the slider which you may find useful.

USB Monitors

Iris was the first software which was working also on USB monitors and monitors connected from docking station like DisplayLink. I made this with the help of new API I created back in 2016

This enabled me to access the video card interface at one level higher and change the gamma without actually the need of gamma support through the cable.

Well, I guess f.lux was really inspired by this because in their new f.lux 4 they made this groundbreaking innovation with a fix for USB monitors.

I guess this is no more innovation of Iris, but nevermind. I am making backlight level control right now which is 10 times more effective than any gamma approach and also reduces battery life πŸ™‚

Blue mouse

There was this problem in f.lux that there was no way to change the cursor color and it’s always bright:

Iris was the first software to add an option for changing the color of the cursor also like this:

I called this software cursor and it can be enabled from the System page. This setting is also available in the free version of Iris.

With the new version of f.lux, they also added this option to the interface. There is this option in f.lux 4:

The problem isn’t exactly this.

After I added this a lot of people wrote to me that the cursor is not shown when they play fullscreen games.

This is a problem with which f.lux still doesn’t have a solution. In Iris, there is the Mouse pausers page.

From here you can select which programs to disable the software mouse when running.

With this, you can enjoy orange cursor when you browse your PC and you will also be able to see the cursor when you play games in fullscreen.


One more downside of f.lux is that the program is available only in English.

Since Iris has distributors all over the world it’s available in many other languages.

Best translations are English, Bulgarian, Chinese and Japanese, but Iris is available in 17 different languages at the moment and everyone who wants to help with the localization to his native language can do this from the How to translate Iris page πŸ™‚


The users of f.lux are really great at helping each other in the forum there seems to be no official documentation of how to use the program.

The closest thing to documentation is the f.lux FAQ page.

In Iris, all things have blue information labels that open the corresponding help page for every feature.

You can also find all Iris help pages from the Help page.

Improvements in f.lux v4

F.lux 3 was really great in that it was super lightweight and simple to use.

F.lux 4 came with major improvements like the DisplayLink USB monitors support, software mouse and the better custom control of values.

Aside from this, the UI seems a little overcomplicated now.

Why Iris is better than f.lux?

It’s not only the Blue light.

There is also PWM flicker, Font rendering, Subpixel flicker,Β Temporal dithering, Rests, and ease of use.

Iris takes care of all things related to eye health and sleep.

While I understand why some people don’t like Iris, because it’s not absolutely free, you need to understand that to make money companies either show you ads constantly, sell your user data or just make great paid products.

With Iris, I wanted to create a great free product and great paid product. The so-called freemium model.

Bellow I also created one table with a comparison of Iris mini, Iris, Iris mini Pro, Iris Pro, and f.lux. I hope you enjoyed this article πŸ™‚

Iris Pro Iris mini Iris mini Pro f.lux 3 f.lux 4
Blue light
Custom time
0% Blue light
Automatic Brightness
Break reminding
Font rendering
Moon Sleep latency
Color pausers
Part screen Blue light reduction
Color schemes
USB Monitors
Orange mouse

The fields marked with are partly on not really well-implemented features.

I did change Iris to be free trial recently but you can still download free Iris from these links: Windows, macOS

Final words

If you liked or hated this article share it with friends πŸ™‚

I tried to make some basic comparison between Iris and f.lux.

We work really hard to make Iris the best blue light filter and eye protection software. And it’s not only us, but we also talk every day with users. We also have more than 500+ only positive Facebook reviews and Google reviews and are really proud of this πŸ™‚

I also give you my word that if you for some reason buy Iris and are not 100% satisfied with the product we will either fix all your problems or return your money. You can read also about our Refund promise.

Daniel Georgiev
Chief Executive Officer (CEO)
Iris Technologies EOOD

7 thoughts on “Best alternative to f.lux

  1. Hi.
    Does Iris work with multiple monitors?
    At work I have a tower computer with three monitors.
    At home I have a docking station for my laptop – plus two monitors.
    Can you tell me how Iris works in these situations?
    Is there a trial software?
    Thanks in advance for your response.

    1. UPDATE:
      High-level API is enabled by default in the newest version so it will work out of the box πŸ™‚

      Iris is free for 7 days and we don’t ask for payment details or anything. When it expires you can delete it if you don’t like it and not worry about canceling a subscription.

      I know from my experience that I hate apps which ask for my debit/credit card details and we don’t do this

      You can download Iris for free from our homepage:

      and you can always write to us if you need some feature or want help with something πŸ™‚

  2. Hi there — I’m trying to use a GUD300 Displaylink with a Mac and your program isn’t working. If you can get it to work I’d love to buy your software. The external monitors do not change colors. I installed the GUD300 driver software and it didn’t work. Do you have a workaround in place?

Leave a Reply

Your email address will not be published. Required fields are marked *