Carrot2 is an Open Source Search Results Clustering Engine. It can automatically organize (cluster) search results into thematic categories:

Carrot2 provides an architecture for acquiring search results from various sources (YahooAPI, GoogleAPI, MSN Search API, eTools Meta Search, Alexa Web Search, PubMed, OpenSearch, Lucene index, SOLR), clustering the results and visualising the clusters. Currently, 5 clustering algorithms are available that are suitable for different kinds of document clustering tasks.

Thanks to its flexible architecture, high quality and a friendly BSD-like license, Carrot2 has been successfully used in a number of commercial and research applications and resulted in a number of interesting publications. To get started, please have a look at live demos and the downloads section. If you have any questions or comments about Carrot2, please let us know.