CalcPad is a free software for mathematical and engineering calculations available for both desktop and cloud.
It supports real and complex numbers, physical units, variables, functions of multiple arguments, graphing and numerical methods.
You can add images and 'comments', with simple text, Html, CSS, SVG etc. Put "?" where you need to enter values and automatically generate beautiful Html input forms, out of your source code. Then you can lock and hide your code, by saving a cpdz file.
Some advanced features are also available: conditions (#if, #else, #end if), cycles (#repeat, #loop), output visibility control (#hide, #show), content folding, smart rounding, smart brackets, etc.
The results are presented in professional looking Html reports. All formulas and values are included and can be thoroughly checked. That makes Calcpad a perfect solution for development of engineering spreadsheets.