SpeedCrunch - SpeedCrunch. SpeedCrunch is a high-precision scientific calculator featuring a fast, keyboard-driven user interface. It is free and open-source software, licensed under the GPL. Download Documentation Donate .

Integral Calculator - Calculate Integral Online and Free

Qalculate! - Qalculate! is a multiplatform multi-purpose desktop calculator.

Rule of 3 Calculator - Apply the mathematical Rule of Three in an easier, faster and more practical way!

Numi App - Numi is a beautiful text calculator for Mac.

WolframAlpha - WolframAlpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.