Orange – Interactive Machine Learning and Data Viz Toolbox (orange.biolab.si)

this looks... too good to be true. there's no way a free piece of software has all of these features and actually works. but really outside of educational purposes I don't see the use case. serious users will reach for R or python or even Matlab. but it looks great for teaching a high school data analysis class (or something like that).

I like how their interface is similar to Grasshopper's graphical algorithm editor for Rhino 3-D.

The alternative to this is probably weka https://en.m.wikipedia.org/wiki/Weka_(machine_learning)

FWIW weka is a well-designed system works great for many tasks. Especially if the user cannot code.