MaxNit is a tiny macOS menu-bar app that unlocks the extra brightness of your Liquid Retina XDR display — for your desktop, apps and browser. Not just HDR video.

What it does

XDR and HDR-capable displays can get noticeably brighter than normal, but macOS usually reserves that headroom for HDR video. MaxNit lets you use it for everything: your desktop, apps, browser — anything on screen. A simple Low / Medium / High control sets how much of that extra brightness to use.

It's built to be safe: it never disables or bypasses any display protection (see below).

How it works

The app lays an invisible, click-through layer over your screen that signals to macOS that there's bright HDR content present. That prompts the system to tap into the display's spare brightness headroom — the same headroom HDR video uses — and the app uses it to brighten the whole screen uniformly while preserving color.

The key point is that the app only signals that brighter content is there. macOS firmware still controls the actual backlight and clamps it for heat and power, so it simply won't go brighter than is safe. No brightness limits, gamma tables, or thermal protections are touched.

Use

• Runs in the menu bar (no Dock icon) and always starts off.
• Left-click the sun icon to toggle MaxNit on and off.
• Right-click (or ⌃-click) opens a menu with a Low / Medium / High brightness control. Low and Medium are gentle fixed steps; High uses the full headroom the panel reports at the current system brightness.
• Keyboard toggle: press ⌃⌥⌘B at any time to toggle it on or off.

Build

Requires macOS 13+ and the Xcode command-line tools.

./build.sh
open build/MaxNit.app

This produces an ad-hoc-signed .app — no special entitlements needed.

Tests

A Package.swift is included so the core logic can be unit-tested:

swift test                       # run the suite
swift test --enable-code-coverage

The safety- and correctness-critical logic — boost clamping, anti-flicker smoothing, the Low/Medium/High level math, and display-change detection — is covered by the test suite. The UI and graphics glue is validated by building and running the app itself.

License

MaxNit is released under the MIT License. It's provided "as is", without warranty of any kind, and the authors accept no liability for its use.