Shrinker

Based on the UPX exe compactor, Shrinker is a simple and straightforward application that gives you the possibility to reduce the size of large and very large executable files, whether they originate from personal software projects or other sources.

Simple setup and GUI

By the look of the installation package, it's obvious that the utility hasn't received updates for a long time, due to the fullscreen mode and gradient background color that take us back to the setup files in classical Windows.
As far as the interface is concerned, Shrinker doesn't put emphasis on graphical elements. It has a single window that holds the handful of options put at your disposal, making it easy to navigate. At least you don't have to depend on multiple panels to waste time locating options to swiftly carry out tasks.

Add executable files to compress

You can resort to the built-in file browser to find and open the .exe file of any application, whether it's installed or wrapped in a portable package, as well as press the Tab key to compress the item seamlessly.
Worth mentioning is that the application doesn't create new files but compresses the original items instead. Therefore, you might be interested in manually performing backups before using Shrinker, since it doesn't come with a built-in feature for this task. This way, you can keep a copy of the original executables in case error occur that render the files corrupt, or if you're simply not pleased with the new size of the compressed files.
Unfortunately, the app doesn't support batch processing, which means that you're restricted to compressing only one file at a time. This might be inconvenient to users looking to reduce the size of multiple executables at once.

Evaluation and conclusion

It didn't put a strain on the computer's performance in our tests, using low CPU and RAM. However, an error dialog popped up when we attempted to compress files, failing in the task. This probably happened because Shrinker hasn't received updates for a considerable amount of time and likely has compatibility issues with newer Windows versions.