[ForceBru]

According to https://github.com/rawbytess/hissab, it's not even close to being an alternative to Wolfram. Hissab is described as "A strict, unit-aware natural-language calculator" and its syntax looks nothing like Wolfram. It reminds me of Wolfram Alpha, though.

[prenx4x]

Its not trying to achieve a feature parity with wolfram or mimic it. Its just an alternative to do calculations and may meet somewhere in the middle.