Yet there is hardly any computing system that can replicate Mathematica tooling capabilities.
One would expect 37 years would be enough to create such alternative.
Jupiter notebooks aren't the same.
Honest question: I think Maple is really a competitor, even if less known.
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.