Doesn’t feel and look like Soulver (at least according to its introduction video), but InstaCalc seems to be something similar.
You can name and share calculations (even without login): http://instacalc.com/26664
It’s row-based, and you can reference the results from rows in other rows.

Natural language can be used like 15 million
, 10m
, and 3k
, but it doesn’t support "four" or "one million".
It supports unit conversion, e.g.:
1 foot in cm
= 30.48 cm
1 foot/sec in cm/hour
= 109,728 cm/hour
15 apples/day in hours per apple
= 1.6 hours / apple
1 USD in EUR
= 0.7848 EUR
1 hour in days
= 0.04166666667 days
It has some functions useful for programmers, and it even supports if
, and can output strings depending on calculations, e.g.:
if (BMI < 18.5 ) {diagnosis = "underweight"} else if (BMI < 24.9){"normal weight"} else if (BMI < 29.9){diagnosis ="overweight"} else {diagnosis ="obese"}