This Standard Deviation Calculator is built for google workspace to find 
- Standard Deviation
- Variance
- Sum
- Mean
- Sum of differences 
without leaving tab.
It calculates above values via javascript which it shows result instantly.
The input area is very intelligent it won't let you entered wrong value even if you leave input empty in alerts you to fill it first.
you can switch to population to sample and vice versa without entering data again.