f.lux Download: Where to Get It Safely on Mac, Windows and Linux

Where to download f.lux, by platform

Mac. Get the Mac download from justgetflux.com. f.lux runs from the menu bar once it is installed.

Windows. Get the installer from justgetflux.com, or install f.lux from its Microsoft Store listing, which is published for f.lux and updates through the Store. Either one is the real f.lux.

Linux. f.lux's Linux page offers xflux, a command line daemon, as compiled downloads, the latest a 64-bit build dated September 2013. The open source fluxgui applet that people often install with it now uses Redshift by default, because its README says xflux has not worked on most modern systems since 2016. On a current Linux desktop, the night mode built into GNOME or KDE Plasma is usually the simpler choice. Our page on whether f.lux is open source covers the Linux side in detail.

iPhone and iPad. There is no f.lux app in the App Store. Use Night Shift, which is built into iOS.

f.lux on a MacBook: what to know before you install

The f.lux download for a MacBook is the same Mac download from justgetflux.com, and the process is the usual one: open the download, move f.lux to Applications, launch it and set your location so it knows when the sun sets where you are. CircadianShield's walkthrough of every f.lux setting on macOS covers what to change after that first launch.

macOS already has Night Shift, which warms the screen on a schedule. If you install f.lux, turn Night Shift off in System Settings, under Displays. Two warming filters can stack, which makes the screen warmer than either app intends and makes it harder to tell which one is in charge.

f.lux changes color temperature. It does not dim the screen below the brightness slider on a Mac. If that is what you want, our page on f.lux brightness and its limits explains what f.lux can and cannot do there.

Is the f.lux download safe?

From the official sources, yes, as far as anyone outside the developer can tell. f.lux is closed source, so you are trusting its developer and track record rather than code you can read. That record is long: f.lux was released in February 2009 by Michael Herf and Lorna Herf, is developed by F.lux Software LLC, and in November 2015 f.lux said its desktop software had been downloaded more than 15 million times.

The risk is where you get it. Download portals rank well for this search, and a repackaged installer is an extra party you have to trust. Get f.lux from justgetflux.com or the Microsoft Store listing and nowhere else.

The free personal build is not silent. f.lux's Corporate Edition page lists disabled automatic updates and disabled interactions with the f.lux website as corporate differences, which tells you the personal build checks for updates and contacts the f.lux site.

Is f.lux free?

Yes, for personal use, on macOS, Windows and Linux. The f.lux FAQ also allows the free version on a work computer if you have the right to install software and your employer approves. A company that recommends f.lux to employees, wants IT to control updates, or manages many installs buys the Corporate Edition, which is Windows only. Its page lists $24 per device for the first 10 devices and $12 per device from the 11th, with one year of updates included.

What is the latest version of f.lux?

The current version is the one justgetflux.com offers, and the personal build checks for updates on its own, so an installed f.lux stays current. Version numbers on download portals are often behind, which is one more reason to download from the developer.

f.lux not working? What to check

• It is not running. f.lux only works while it is open. Look for it in the Mac menu bar or the Windows system tray, and set it to start when you log in.
• The location is wrong. f.lux times its changes to sunset where you are. If it warms the screen at the wrong time, set your location again in its settings.
• Another filter is on. Night Shift on a Mac or Night Light on Windows can fight with f.lux or stack on top of it. Turn the built in one off. Our page on f.lux vs Windows Night Light compares the two.
• It is paused. f.lux can be disabled for an hour, until sunrise, or for a full screen app. Check its menu before reinstalling.
• It is out of date. Reinstall from justgetflux.com to get the current build.

Is f.lux worth it, or is there a better option?

For a free, warmer screen in the evening, f.lux is a reasonable choice and has been for years. Where it stops is color temperature: it does not track the sun's real elevation through twilight, it does not measure light the way the CIE S 026 Melanopic EDI standard does, and on a Mac it does not dim below the brightness slider. A warmer screen can feel more comfortable in a dark room, but no screen filter is a medical treatment. Our full f.lux review weighs what you get after the download against those limits.

CircadianShield is the paid option we make for people who want more than that. It follows the sun's real elevation across 11 twilight phases, calibrates to Melanopic EDI rather than to Kelvin, and dims below the operating system brightness floor. It is a native app for macOS 14 and later and Windows 10 and later. Screen filtering and health scoring run entirely on your computer, and no screen content or personal data leaves it. The app sends optional anonymous usage and technical diagnostics, which you can switch off in Settings.

Compare them side by side in Iris vs f.lux vs CircadianShield, or see every option in our f.lux alternative roundup.

f.lux download: frequently asked questions

Where do I download f.lux?

From justgetflux.com, the developer's site, for macOS, Windows and Linux. On Windows, its Microsoft Store listing is also official. Avoid download portals.

Is f.lux software safe?

From justgetflux.com or the Microsoft Store, f.lux has a long public record: released in February 2009, with more than 15 million desktop downloads by November 2015. It is closed source, so you are trusting the developer rather than code you can audit.

Is f.lux free?

Yes, for personal use on macOS, Windows and Linux. Companies managing it across many devices buy the Windows only Corporate Edition, listed at $24 per device for the first 10 devices and $12 per device after that.

Does f.lux work on a MacBook?

Yes. Download the Mac version from justgetflux.com, move it to Applications and set your location. Turn off Night Shift so the two filters do not stack.

Why is f.lux not working?

Usually it is not running, it is paused, the location is wrong, or Night Shift or Night Light is on at the same time. Reinstalling from justgetflux.com fixes an outdated build.

What is the latest version of f.lux?

Whatever justgetflux.com offers today. The personal build checks for updates itself, and download portals often list older versions.

Is f.lux worth it?

For a free warmer screen, yes. If you want sun-tracked twilight phases, Melanopic EDI calibration or dimming below the brightness slider, a paid app such as CircadianShield does more.