Black Light is a macOS accessibility and productivity utility that overlays configurable visual filters on your entire screen, making it easier to read, reduce eye strain, or simulate how your display appears to users with different types of colour vision deficiencies.
What is Black Light?
Black Light is a lightweight Mac app by Michel Fortin that sits in your menu bar and lets you apply full-screen visual effects — colour inversions, tinting, contrast boosts, and colour blindness simulations — on top of everything your Mac displays. Unlike f.lux or Night Shift, which simply warm the colour temperature at sunset, Black Light gives you deliberate, on-demand control over how your screen looks at any moment.
I first reached for it as a design sanity check: before shipping a UI, I can flip through deuteranopia and protanopia filters in seconds to see whether my colour choices hold up. It has since become a permanent fixture in my menu bar for late-night coding sessions too.
What does Black Light do best?
Black Light excels at its two killer tasks: colour-blindness simulation for designers and quick inversion for eye-strain relief in dark environments. Both are instantaneous — a single menu-bar click, no lag, no permission drama.
- Colour blindness simulation — deuteranopia, protanopia, and tritanopia modes give designers an honest picture of whether their palette is accessible without leaving Figma or Xcode.
- Smart inversion — inverts screen colours while optionally preserving natural-looking photos and video, which is the key thing macOS's own Smart Invert misses in edge cases.
- Tinting and contrast overlays — useful for reducing the harshness of an all-white document editor at 2 a.m., or boosting contrast when working in strong ambient light.
- Instant toggle — keyboard shortcuts let you flick effects on and off mid-task without touching the mouse.
Where it falls behind: it cannot selectively filter one window (the effect is always full-screen), so if you need per-app adjustments you will want to pair it with macOS Display Accessibility settings.
How much does Black Light cost?
Black Light is a paid app, priced as a one-time purchase — no subscription. The developer sells it directly from michelf.ca, which means no App Store cut and typically faster updates. A free trial is available so you can confirm it does what you need before buying.
Who should use Black Light?
Designers and frontend developers will get the most obvious value from the colour-blindness simulation modes — it is genuinely faster than exporting screenshots into a separate accessibility checker. Accessibility auditors, writers who prefer low-luminance reading conditions, and anyone who finds macOS's built-in inversion too blunt will also find a home for it in their workflow.
If you are purely looking for blue-light reduction, f.lux or the built-in Night Shift handle that more gracefully. If you only need occasional display tweaks, macOS Accessibility settings (System Settings → Accessibility → Display) cover some of this ground for free. Black Light earns its keep when you need to toggle between multiple effects quickly and repeatedly — something neither of those alternatives is designed for.
What are the best Black Light alternatives?
The closest rivals depend on which feature you are after. For colour-temperature shifting, f.lux remains the gold standard and is free. For full-screen colour inversion, macOS ships Smart Invert natively (Control+Option+Command+8). For professional colour-blindness simulation during design review, Sim Daltonism offers a floating magnified preview window rather than a full-screen overlay — useful when you want to see affected versus unaffected side by side. Lungo and Amphetamine have nothing to do with colour but often appear alongside Black Light in the same power-user menu bar, which says something about its audience.
Black Light occupies a pragmatic middle ground: it does more than a single-trick tinter but stays far leaner than a full accessibility testing suite.
How does Black Light compare to macOS Smart Invert?
Smart Invert, built into macOS, tries to exempt images and video from inversion — but it can misidentify UI elements and leave artefacts in apps that render custom surfaces. Black Light's inversion gives you explicit control over what gets exempted, and it bundles filters Smart Invert does not have at all: colour blindness modes and tinting. For most accessibility use cases Black Light is the more flexible tool; Smart Invert wins only on price (free) and zero-install convenience.
