SIMON is described as 'powerful, flexible, open-source and easy to use knowledge discovery application'. There are more than 10 alternatives to SIMON for Windows, Linux, Mac, Online / Web-based and BSD. The best alternative is Orange, which is both free and Open Source. Other great apps like SIMON are KNIME (Free, Open Source), RapidMiner (Freemium), WEKA (Free, Open Source) and Neural Designer (Paid).
Orange is an open-source, cross-platform data mining and machine learning suite. It features visual programming as intuitive means of combining data analysis and interactive visualization methods into powerful workflows.
RapidMiner (Community edition) is a data mining software. It was formerly known as "YALE". You can use RapidMiner as a stand-alone application for data analysis, or integrate it as a data-mining engine into your own products.
Neural Designer is a software tool for advanced analytics. It includes tools for descriptive, diagnostic, predictive and prescriptive analytics. It allows you to get actionable insights resulting in smarter decisions and better business outcomes.
ELKI: "Environment for Developing KDD-Applications Supported by Index-Structures" is a development framework for data mining algorithms written in Java. It includes a large variety of popular data mining algorithms, distance functions and index structures.
QIWare is an agile analytics solution that delivers a complete suite of capabilities to support end-to-end data mining cycle. Simplify data preparation and modeling while increasing business productivity, minimizing human error, and significantly improving usability.