Wolfram Alpha "is an engine for computing answers and providing knowledge. It works by using its vast store of expert-level knowledge and algorithms to automatically answer questions, do analysis, and generate reports." Wolfram Alpha was developed by Wolfram Research, the makers of Mathematica.
Wolfram Alpha is free to use. Swarthmore College users have free access to Wolfram Alpha Pro.
File uploads – can process your own data
Interactive output using Computable Document Format (CDF)