From the St. Claire Software website:

Quickly scan your disk for applications, see which ones are 32-bit, and find upgrade information with the click of a button.

Go64 makes it easy to plan for the future.

And yes, it’s FREE!

Find out which apps will stop working after Mojave and why. Does deep scans of apps, e.g. checking embedded frameworks and helper app bundles.

I used to use their Default Folder X about 10 years ago, and still use Jettison. I trust the dev.