Software calculators

WolframAlpha is an online knowledge engine developed by Wolfram Research that has been around since 2009. It is offered as an online service that answers queries by computing answers from externally sourced data.

software application

UNIX utility which implements an arbitrary-precision arithmetic language

KCalc is a scientific software calculator integrated with the KDE Gear.

basic calculator application made by Apple

cross-platform reverse-Polish calculator program

calculator application for GNOME

calculator as a computer program