Carrot2 is an open source search clustering engine that is incredibly useful in organising search results into sub-topics and showing the number of resources found in each category. It does this by clustering document abstracts and search results, using public search engines from the web or PubMed, into specific themes. Carrot2 can automatically discover groups of related documents and label them with short terms or phrases. You can choose from ‘list’, ‘treemap’ or ‘pie-chart’ view options for a visual organisation of your search results. Please see the examples below.

Search example (web): genetic engineering

Search example (web): genetic engineering

Search example (PubMed): genetic engineering