GeoGebra Classic is described as 'Free online apps bundle from GeoGebra: get graphing, geometry, algebra, 3D, statistics, probability, all in one tool!' and is an app in the Education & Reference category. There are more than 10 alternatives to GeoGebra Classic for a variety of platforms, including Android, iPhone, Online / Web-based, iPad and Windows. The best alternative is Wolfram Alpha, which is free. Other great apps like GeoGebra Classic are fxSolver (Free), Mathpix Snip (Freemium), Photomath (Freemium) and Symbolab Math Solver (Freemium).
Wolfram Alpha is a "Computational Knowledge Engine" - different from a search engine, it answers factual queries directly by computing the answer from structured data, rather than providing a list of documents or web pages that might contain the answer.
Mathway provides students with the tools they need to solve their math problems. With tens of millions of problems already solved, Mathway is the #1 online problem solving resource available for students, parents, and teachers.
Math, part of the Apache OpenOffice suite, is a tool for creating and editing mathematical equations, similar to Microsoft Equation Editor (included in Microsoft Office). The created equations can then be embedded inside other OpenOffice.