Mathway - Mathway is a freemium math solving app that helps you find the solutions to any math problem you can imagine.

WolframAlpha - WolframAlpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.

MyScript Calculator - Perform mathematical operations naturally using your handwriting.

Photomath - Photomath is a mobile app that will give you the ability to test your equations through a simple calculator interface that will fully explain the solution in a step-by-step fashion. Read more about Photomath.

Math.com - Math.

Cymath - Free Step-By-Step Solutions to algebra problems.