OneSecondSolver is described as 'Your personal math tutor. Available right when you need it!' and is an app in the Education & Reference category. There are more than 10 alternatives to OneSecondSolver for a variety of platforms, including Online / Web-based, Android, iPhone, iPad and Windows. The best alternative is Wolfram Alpha, which is free. Other great apps like OneSecondSolver 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.