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ExtLume

Free#22 of 24 in Monitor Control Software

ExtLume: A focused open-source Windows tool for DDC/CI monitor brightness control. Ranked #22 of 24 in Monitor Control Software by our editors (6.2/10); pricing: Open source; best for windows users focused on brightness control.

6.2/10Editor score

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At a glance

Editor score
6.2 / 10
Pricing
Open source
Best for
Windows users focused on brightness control
Paid from
Free
Supported platforms
Windows
Facts checked
20 Sep 2026

Where it wins
- DDC/CI hardware brightness control with software-dimming fallback
- Separate controls for multiple displays and mirrored groups
- Hot-plug rescanning, tray operation, and Windows startup
Where it doesn't
- No input switching or monitor profiles
- No scheduling, CLI/API, or auto-brightness
- Software dimming changes perceived brightness, not backlight power

Our verdict on ExtLume

ExtLume is an open-source Windows tray application for controlling external monitor brightness. It detects active physical displays through Windows DisplayConfig and EDID metadata, then provides separate brightness controls for compatible monitors. The application supports Windows 10 and 11, multiple displays, mirrored-display grouping, built-in and virtual display exclusion, hot-plugging, resume rescanning, system-tray operation, and Windows startup. It is aimed at Windows users who want direct brightness control for external monitors without a broader monitor-management feature set.

Its main strength is the way it handles different display environments. ExtLume prefers hardware brightness control through DDC/CI, while a software-dimming overlay provides a fallback when hardware control is unavailable. Separate controls help distinguish multiple displays, and clone protection plus mirrored-display grouping address common multi-monitor arrangements. The software-dimming mode changes perceived image brightness rather than panel backlight power, so the two control methods have different effects. Display detection and rescanning also support changing monitor setups, including hot-plug and resume scenarios.

ExtLume keeps its scope narrow. The published feature set covers brightness control, display detection, grouping, exclusion, startup, and tray access, but it does not provide input switching, monitor profiles, scheduling, a CLI or API, or auto-brightness. Current public releases are beta builds, and the software is distributed under the MIT License. Choose ExtLume if your priority is open-source brightness control on Windows, especially with multiple external displays. Choose another tool if you need automated brightness changes, saved monitor configurations, input management, or command-line control.

Your product? Our editors can test ExtLume in depth and publish a review, labelled as paid · from $149/mo →

ExtLume pricing

Plans Open sourceFree Free to use — no paid tier required for the core job.

See plans on github.com

ExtLume fact sheet

Free plan	Not verified
Paid from	Free
Supported platforms	Windows
DDC/CI control	Yes
Input switching	No
Monitor profiles	No
Settings scheduling	No
CLI or API access	No
Auto brightness	No
Deployment	Desktop
Platforms	Windows
Support	Community, Docs
Built for	Solo, Small business (editorial estimate)
Pricing	Open source
Website	github.com
Facts checked	20 Sep 2026

Alternatives to ExtLume

See all ExtLume alternatives →

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Featured on iTechGuides

ExtLume is listed in our Monitor Control Software directory. Add the badge to your site — it links back to this page.

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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.

Last updated 7 Oct 2026 · How we research and update