SymCalc - Symbolic Calculator!

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.

PhotoMath is the world's first camera calculator. Just point the camera towards the mathematical expression, and PhotoMath instantly displays a correct result.

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.

Symbolab: equation search and math solver - solves algebra, trigonometry and calculus problems step by step

SymPy Gamma is a simple web application based on Google App Engine that executes and displays the results of SymPy expressions as well as additional related computations, in a fashion similar to that of Wolfram Alpha. For instance, entering an integer will display prime factors, digits in the base-10 expansion, and a factorization diagram. Entering a function will give its docstring; in general, entering an arbitrary expression will provide the derivative, integral, series expansion, plot, and roots. »