fxSolver is described as 'Online math solver, equation library, graphing calculator and science/engineering problem helper' and is a popular Calculator in the education & reference category. There are more than 100 alternatives to fxSolver, not only websites but also apps for a variety of platforms, including Mac, Windows, Linux and Android. The best alternative is SpeedCrunch, which is both free and Open Source. Other great sites and apps similar to fxSolver are Microsoft Office Excel, Wolfram Alpha, Qalculate! and GNU Octave.
Calcpad is a lightweight mathematical platform for cloud and desktop. It parses simple text scripts and converts them into professional Html reports. Supports complex numbers, variables, functions, graphing, units and numerical methods.