Making a brand-new tech purchase doesn’t always carry the guarantee of a perfectly functioning unit. But a tiny Mac app called Screen Test can help you find a defect before it gets too late. Screen Test (version 1.1) is a native macOS utility containing more than 25 patterns and diagnostic tools for evaluating built-in and external displays. It can help reveal dead or stuck pixels, backlight bleeding, and other issues. The app works completely offline, so you don’t have to rely on browser tabs or an internet connection.
Every pixel gets scrutinized
Screen Test fills the display with carefully selected colors, grids, grayscale steps, and other patterns that make subtle panel defects easier to spot. A solid-color cycle can expose pixels that remain permanently dark or stuck on one color, while uniform gray and black screens can reveal backlight bleed and inconsistent brightness across the panel.
Version 1.1 introduces seven additional tools:
- An automated dead-pixel cycle
- A text-resolution chart
- A motion-blur and ghosting test
- Customizable solid-color fills
- Checkerboard contrast patterns
- Grayscale steps
- Editable text for evaluating sharpness.
The motion test should prove especially useful when inspecting a gaming monitor, where slow pixel transitions can leave trails behind moving objects. Text patterns can also highlight subpixel rendering or sharpness problems that become obvious during everyday work, even when games and videos appear acceptable.
Four dollars could protect a much larger purchase
Most core features are available free of charge. A $3.99 lifetime purchase unlocks the remaining advanced options, with no recurring subscription. The Mac App Store lists the download at just 1.5MB and requires macOS 14 or later. Apple’s privacy label also states that the developer does not collect data from the app.
Screen Test cannot automatically certify a display or provide the numerical accuracy measurements produced by a colorimeter. Its developer describes the results as a visual reference and warns that the app does not replace professional testing equipment. However, it can be helpful when buying an external monitor, a new MacBook, or a secondhand display.