>>nsoonh+(OP)
Maybe with the power of a supercomputer, Mathematica can finally launch in less than 30s. I have no idea how a software that still does essentially the same thing as it did in 1988 can be that sluggish.
>>pjmlp+R7
Sage Math? Though I admit, unlike homogeneous Mathematica, it's just a Python glue on multiple smaller projects of different quality and poorly integrated. I wish there was something more like the Wolfram software but there isn't.
>>xvilka+u8
I've used Sage for years to run the backend (calculations/computations/graphics/prototyping) for a multivariable calculus class I teach. It's not perfect, but as a lightweight, Python-style CAS to do all sorts of "standard" calculations, it's very easy to use!