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.
SageMath is a free open-source mathematics software system licensed under the GPL. It builds on top of many existing open-source packages: NumPy, SciPy, matplotlib, Sympy, Maxima, GAP, FLINT, R and many more.
Maxima is a system for the manipulation of symbolic and numerical expressions, including differentiation, integration, Taylor series, Laplace transforms, ordinary differential equations, systems of linear equations, polynomials, and sets, lists, vectors, matrices, and tensors.
Spyder (previously known as Pydee) is a free open-source Python development environment providing MATLAB-like features in a simple and light-weighted software, available for Windows XP/Vista/7, GNU/Linux and Mac OS X.
A simple yet powerful calculator that includes standard, scientific, and programmer modes, as well as a unit converter. It's the perfect tool to add up a bill, convert measurements in a recipe or other project, or complete complex math, algebra, or geometry problems.