SpeedCrunch
Open Source
SpeedCrunch is a high-precision scientific calculator featuring a fast, keyboard-driven user interface.
Calcbot
Freemium
Calcbot is a intelligent calculator and unit converter.
Soulver
Commercial
Soulver is quicker to use than a spreadsheet and smarter and clearer than a traditional calculator.
Compare Qalculate! with alternatives
Compare SpeedCrunch and Qalculate! and decide which is most suitable for you.