This is an unlocked version of the same utility published on my page. In this version you can access and view VBA code. Locked version is free.
Indifference curves depict sensitivity of an output to the two inputs. Each curve corresponds to a fixed output amount and shows at which combination of the two inputs this output amount remains the same (or indifferent, hence the name of the chart type).
The program uses VBA, so make sure you enable macros on your computer when you open the file.