Every screen you own. One slider. All the way down to black.

Download · What it does · Screenshots · Build it · Status

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Your monitor has brightness buttons

They are on the back. There are five of them, none is labelled, and the menu they open was designed in 2009. You are never going to use them.

Duja is a tray icon. Click it, drag one slider, and every display you own dims for real: over DDC/CI on your externals, over the native backlight on your laptop panel. The same signal those buttons send, minus the archaeology.

Hardware zero is not the bottom

Most panels give up somewhere around "still too bright at 2am". Duja keeps going. Past the hardware floor it takes over in software, so one continuous slider runs from sunlit desk to true black, and you cannot see the seam where the handoff happens.

What it does

• A slider that tells the truth. 20 % looks 20 % bright, on any panel, whatever its floor. No two monitors disagreeing about what "half" means.
• Multi-monitor, properly. Link them all to one slider, or tune each one and let Duja remember. Settings are keyed to the display itself, so unplug, dock, reboot, and your levels come back exactly where you left them.
• Weighs nothing. No Electron, no webview, no bundled browser, no background service. About 24 MB of RAM, and zero CPU while it sits there being useful.
• Nice to look at. Native light and dark themes, five accent colours, and a flyout that opens right at the tray instead of in the middle of your screen.
• Power tools in the box. Global hotkeys, HDMI and DisplayPort input switching from the tray, and dujactl for people who script their desk.
• Quiet by design. No telemetry, no account, no ads, no upsell. One optional update check a day, and it never installs a thing behind your back.

Free, open source, and written in Rust because your brightness slider should not need a garbage collector.

Screenshots

Flyout (dark)	Flyout (light)

_{Settings (dark)}

Get it

Everything lives on the Releases page.

	grab this	then
Windows 10/11	duja-setup-<version>.exe	Run it. Per user, no admin prompt. Prefer no installer? Take the .zip and run duja.exe from anywhere.
macOS 11+	duja-<version>-macos-universal.dmg	Drag Duja to Applications. Intel and Apple Silicon in one bundle.
Linux x64	duja-<version>-linux-x64.tar.gz	Extract, put duja and dujactl on your PATH, run dujactl doctor.

First run may need one extra click (Windows and macOS), and Linux likes a checkup

Windows. The binaries are not code signed yet, so SmartScreen may say "Windows protected your PC". Choose More info, then Run anyway. If you would rather trust maths than a dialog box, verify the download first (see the fine print).

macOS. The app is signed ad hoc rather than with a Developer ID, so macOS blocks the first open of a downloaded copy. Allow it under System Settings → Privacy & Security → Open Anyway. macOS 15 removed the old Control-click → Open trick, so guides that still recommend it are out of date. dujactl rides inside the bundle; symlink it if you want it on your PATH:

sudo ln -s /Applications/Duja.app/Contents/MacOS/dujactl /usr/local/bin/dujactl

Linux. Run dujactl doctor before anything else. Linux sessions vary more than the other two platforms, and doctor prints exactly what yours can do and what to install if something is missing. Three things worth knowing up front: the tray needs a StatusNotifierItem host (native on KDE Plasma, an extension away on GNOME); external monitors need the i2c-dev module and permission on /dev/i2c-*, which doctor will talk you through; and global hotkeys are not available on Linux at all, so Duja greys those rows out and tells you why instead of pretending. packaging/linux/README.md has the full story.

Package managers (winget, Scoop) are planned once the release stabilises.

Note

Windows is the road-tested one. macOS and Linux ship as unverified previews: the code is complete and green on CI for both, and nobody has yet run either build on the hardware it targets. Treat a first run as an experiment, and please tell us what happened. docs/STATUS.md keeps the honest scoreboard.

Scriptable, too

dujactl list                     # every display, with its id and level
dujactl set all brightness 30    # the whole desk, in one go
dujactl input <id> hdmi1         # switch inputs without touching the monitor
dujactl doctor                   # what your machine can actually do

Build it yourself

cargo build --workspace
cargo test  --workspace

That is the whole ritual. The toolchain is pinned in rust-toolchain.toml, and CONTRIBUTING.md covers the rest. Cutting a real release is docs/release-checklist.md, driven by .github/workflows/release.yml.

Under the hood, for the curious

Rust and Slint with a software renderer, so there is no browser hiding in your tray. 1,489 tests, 6 fuzzers, three green CI lanes, a lint wall that bans unwrap in shipping code, and an adversarial review of every single pull request. Every release carries checksums, a minisign signature and a GitHub build provenance attestation.

The architecture decisions are written down in docs/adr/, including the ones that turned out to be wrong.

The fine print

• Verify a download: SHA256SUMS plus a .minisig for every artifact. The public key and the commands are in SECURITY.md.
• A monitor misbehaving? Run dujactl doctor --report and file a quirk report. Those reports feed the built-in quirks database that makes Duja work on imperfect hardware, which is most hardware.
• License: MIT or Apache-2.0, your choice. UI built with Slint under its Royalty-Free license.