Integral Calculator is described as 'Solve definite and indefinite integrals with ease using our free online calculator. Calculate double and triple integrals and get step by step explanation for each solution' and is a Calculator in the Education & Reference category. There are more than 100 alternatives to Integral Calculator for a variety of platforms, including Windows, Android, Mac, Online / Web-based and iPhone. The best alternative is SpeedCrunch, which is both free and Open Source. Other great apps like Integral Calculator are Wolfram Alpha (Freemium), Qalculate! (Free, Open Source), fxSolver (Free) and Numi (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.
Qalculate! is a multi-purpose cross-platform desktop calculator. It is simple to use but provides power and versatility normally reserved for complicated math packages, as well as useful tools for everyday needs (such as currency conversion and percent calculation).
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.
Soulver is a smart notepad with a built-in calculator. It gives instant answers to any calculations it finds in your text. It's a better way to work stuff out than with a traditional calculator, and a more lightweight tool for quick calculations than a spreadsheet.