Very handy rapid spreadsheet-style mortgage calculator. This app. will enable the user to display his/her mortgage parameters, while at the same time store the currently entered details for subsequent use. No need to keep re-entering those details each time. However, those details can be altered at any time and there is even a provision to make payments towards the principal at any date chosen.
Nice feature is that the user, may review any detail changes and can see clearly what great effect can be had, by early payments to principal and/or decreasing the payment intervals (i.e. 30 days payments down to 14 days), can have significant financial savings on interest paid by mortgage completion, while at same time reducing the amortisation years.