Launch Services (Mac Registry Browser)
This is an analysis tool meant for developers and advanced users.
It uses the macOS Launch Services API to perform lookups of bundle IDs and file extensions.
Additionally, it has a browser for the current system's UTI hierarchy (though it can also open the so-called lsregister dumps saved on a different computer - see the Help menu for details).
There is no further documentation. If the commands are not self-explanatory to you, it's probably not an app that you need.
Sample Screen Shots
More Resources about Launch ServicesBlog post about lsregister (The Eclectic Light Company)
Current version: 2.1.3, requires Mac OS X 10.10 or later (Release Notes)