LightBulb for Windows

Quick summary

LightBulb is a free, open-source utility for Windows created by indie developer Alexey Golub. It adjusts the gamma and color temperature of your monitor automatically throughout the day to reduce blue light exposure and help lower eye strain.

How it works

LightBulb shifts your display’s color balance from cooler bluish tones during daytime to warmer orange hues in the evening. The transitions are driven by the current time (and optionally your location) so the screen tint changes gradually from morning through night, similar to other blue-light reducers like F.lux and CareUEyes.

Controls and customization

You configure and enable LightBulb from the system tray. Key controls include:

• A slider that defines how long the screen takes to transition between the daytime and nighttime temperatures
• A control for the preferred nighttime color temperature
• A setting for the desired daytime color temperature
• A 24-hour preview so you can see the planned tint changes before applying them
• An application whitelist to exempt programs that need accurate colors
• Keyboard shortcuts for quick adjustments without opening the settings
• An option to manually set your location instead of using automatic detection

Comparison with F.lux

Functionally, LightBulb serves as a free, open-source counterpart to F.lux. Both automatically modulate screen gamma based on time and location, and both aim to reduce eye fatigue by warming the screen in low-light hours. LightBulb matches F.lux in being lightweight and easy to use, but F.lux still provides finer, more granular control over color-temperature adjustments for users who want precise tuning.

Pros and cons

Pros:

• Free and open-source
• Lightweight with an intuitive interface
• Automatic scheduling with optional manual location control
• App whitelist and global hotkeys

Cons:

• Less precise control over color-temperature fine-tuning compared with F.lux

Recommendation

If you want a straightforward, no-cost alternative to commercial blue-light filters, LightBulb is worth trying. It delivers the core features most users need and is simple to set up; just keep in mind that power users who require very detailed color adjustment may prefer F.lux.