Carrot2 is a search interface with its own start and result page. The special focus of the search engine is the preparation of results. The results are assigned thematically to different categories as well as graphically presented in cicles and foam trees.

Today the Swiss search engine etools is used. In the past, the search engines MSN Live Search/Bing and Yahoo were also available. The search engine was developed by Dawid Weiss and Stanislaw Osinski at Pozna´n University of Technology.

Various clustering methods are available: Suffix tree clustering (STC), k-means, Lingo (an own development of the Carrot2 developers), by URL and by Source.

Language English

Launched 2008
Closed No

Developer Weiss, Dawid and Stanislaw Osinski

Country of Origin Poland

2008 - [...] Weiss, Dawid and Stanislaw Osinski

Topic Universal

Region No Limitation

Technical functionalities
Clustering SeEn
Search Interface / Search API

Used SeEn
MSN Live Search

Older Version Internet Archive / WebCite

Wikipedia: »Carrot² is an open source search results clustering engine. It can automatically cluster small collections of documents, e.g. search results or document abstracts, into thematic categories. Apart from two specialized search results clustering algorithms, Carrot² offers ready-to-use components for fetching search results from various sources. Carrot² is written in Java and distributed under the BSD license. [...]

The initial version of Carrot² was implemented in 2001 by Dawid Weiss as part of his MSc thesis to validate the applicability of the STC clustering algorithm to clustering search results in Polish. In 2003, a number of other search results clustering algorithms were added, including Lingo, a novel text clustering algorithm designed specifically for clustering of search results. While the source code of Carrot² was available since 2002, it was only in 2006 when version 1.0 was officially released. In the same year, version 2.0 was released with improved user interface and extended tool set. In 2009, version 3.0 brought significant improvements in clustering quality, simplified API and new GUI application for tuning clustering based on the Eclipse Rich Client Platform.« Source

Teacher Librarian Help (Last visit: 2015): »Carrot2 organizes your search results into topics. Presents it as a circle (doesn’t always work) or as a foam tree (see below). A great alternative to the now non-existent Google Wonder Wheel because it helps students refine search and gain an overall impression of a topic.« Source


Critical points

Features & Functionality


Example results page for "Data Mining" Source

References & further Publications

Wikipedia (EN):
Wikipedia (Others): n.a.

Other Sources

STANISLAW OSINSKI, DAWID WEISS: Carrot2: An Open Source Framework for Search Results Clustering. 26th European Conference on Information Retrieval (Poster session), Sunderland, United Kingdom, 2004. URL:
DAWID WEISS, JERZY STEFANOWSKI: Web search results clustering in Polish: experimental evaluation of Carrot. In: Advances in Soft Computing, Intelligent Information Processing and Web Mining, Proceedings of the International IIS: IIPWM´03 Conference, Zakopane, Poland, 579 (vol. XIV), 2003, pp. 209—220. URL:
JERZY STEFANOWSKI, DAWID WEISS: Carrot2 and Language Properties in Web Search Results Clustering. In: Lecture Notes in Artificial Intelligence: Advances in Web Intelligence, Proceedings of the First International Atlantic Web Intelligence Conference, Madrit, Spain, vol. 2663, 2003, pp. 240—249. URL:
DAWID WEISS: Carrot2: Design of a Flexible and Efficient Web Information Retrieval Framework. Third International Atlantic Web Intelligence Conference (AWIC 2005), Lodz, Poland, 2005, pp. 439—444. URL:
Ian Milligan (2013): Clustering Search with Carrot2 URL:
Carrot² project website URL:
Website: Dawid Weiss URL:
Website: Stanislaw Osinski URL:
STANISLAW OSINSKI, JERZY STEFANOWSKI, ET AL.: Lingo: Search Results Clustering Algorithm Based on Singular Value Decomposition. In: Advances in Soft Computing, Intelligent Information Processing and Web Mining, Proceedings of the International IIS: IIPWM´04 Conference, Zakopane, Poland, 2004, pp. 359—368. URL:

Created: 2015-09-05