BlackScreen

BlackScreen is a simplistic piece of kit developed in the Java programming language, which can be make the screen black instantly by clicking a button. It was designed as an accessible means of relaxing your eyes to take a break from working with bright monitors.

Make the screen black to take breaks from work

However, the application can also be used to quickly hide the screen contents from friends or co-workers who typically snoop around when you want to leave your workstation unattended for just a couple of minutes without having to lock it with a password.
The interface of the program doesn't have visually striking elements but takes a straightforward approach. There's only one, large button available, which immediately turns the screen black when clicking on it.
After this step, BlackScreen automatically exits. To go back to the desktop, you just have to move the mouse or click a button or key.

Needs Java to work properly

Besides the Java Runtime Environment, you don't need to set up anything else. The program is offered in a single executable .jar file that can be copied to the hard drive or flash disks to launch the tool seamlessly on any machine with Java.
Unlike many installers, it doesn't add new entries to the system registry or generate files on the disk on its own. You just have to delete this one file if you're interested in uninstalling the software product.

Evaluation and conclusion

Although the developer made no recent updates, we didn't have any trouble getting BlackScreen to run on the latest editions of Windows and Java. Unsurprisingly from such a compact program, it had small impact on the computer's performance, consuming low RAM and CPU.
It didn't hang, crash or indicate errors. Thanks to its intuitive GUI, BlackScreen can be easily used for making the screen black with little effort.