Not a fortnight seems to go by these days without the announcement of another new Semantic Search engine – hence I though I sit down and draw up my own little list of currently available search engines. The amount of semantics in them isn’t always transparent – hardly any of these search engine providers wants to disclose the ingredients in their recipe. I’ve also included a few search engines or search engine type applications that rely on collective or social intelligence to improve their search results.

If you have heard of any other semantic search engines that are not yet on the list, please leave a comment. They appear in alphabetical order, i.e. in no particular order. The information contained in ‘Notes’ is not intended as an independent evaluation. You might also want to check out the Top 100 list of alternative search engines on ReadWriteWebReadWriteWeb (RWW) is a Web technology blog launched in 2003. RWW covers Web 2.0 and Web technology in general, and provides industry news, reviews, and analysis. Founded by Richard MacManus, Technorati ranked ReadWriteWeb at number 12 in its list of top 100 blogs worldwide, as of October 9, ... – even though a number of search engines – sadly, are no longer online since the article was published in January 2007…

Clusty.com
Claim: “Search done right”
Notes: Allows Clustering of search results and ‘remix clustering’ which they also call ‘clustering 2.0′ which is literally a ‘shaking of the cluster sack”; allows searching in clusters, clustering by topics, sources and domains, presents clusters (with tabs) and results list on results page)
Target Language: English, Japanese, other languages in development
added: July 7, 2008

Cluuz.com
Claim: doesn’t have one, but its claim could be “It’s about the relationships, stupid”
Notes: Cluuz uses the search results of YahooYahoo! Inc. is an American public corporation headquartered in Sunnyvale, California,, that provides Internet services worldwide. The company is perhaps best known for its web portal, search engine, Yahoo! Directory, Yahoo! Mail, Yahoo! News, advertising, online mapping, video sharing, and ... Search Web Service, MicrosoftMicrosoft Corporation is a multinational computer technology corporation that develops, manufactures, licenses, and supports a wide range of software products for computing devices. Headquartered in Redmond, Washington, USA, its most profitable products are the Microsoft Windows operating system ... Live Search, Alexa Web Search and the Technorati Search APIAn application programming interface (API) is an interface implemented by a software program to enable interaction with other software, similar to the way a user interface facilitates interaction between humans and computers. APIs are implemented by applications, libraries and operating systems ... to provide the results, with their visual representation beings its actual selling point – choose from charts, clusters, flash or lists.
Target Language: none specified
added: July 7, 2008

Cuil.com
Claim: “For knowledge, ask Cuil.”
Notes: Started out as the big GoogleGoogle Inc. is a multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program. The company was ... attacker: was launched by former Google employees and is also toting the allegedly biggest index, “three times as many (pages) as Google and ten times as many as Microsoft”; semantically enhanced: search term recommender, related categories, related searched, and really really fast on day 2. The question remains: Wow, How Did Cuil Get So Much Publicity on Day 1?!
Target Language: On day 2, results for German searches were rather lousy
added: July 30, 2008

Evri.com
Claim: Search less, understand more
Notes: has the instruction “Find a Person, Product or Thing” in its search field; entering “Cheese” (probably too banal) shows recommendations like “Chuck E. Cheese’s” (restaurant), “I want someone to eat Cheese with me” (film) and “Bubbles and Cheesecake” (band). You cannot search for things they haven’t in their list of persons products or things, so I cannot search for cheese. Choosing one of the suggested searches instead: Joe Biden. The graph Joe Biden shows links to Sarah Palin, Barack Obama, John McCain, New Hampshire and Katie Couric. There is something that looks like it’s to be used for facted seearch and one of the option ins “Joe Biden > cancelling”. This triggers “Joe Biden > cancelling > Mother-in-law”, “Joe Biden > cancelling > two days”, and “Joe Biden > cancelling > appearance” and may more confusing things. I just cannot figure out what to do with EvriRadar Networks is a San Francisco based company developing semantic web applications for the general public. The company was founded in 2003 by Nova Spivack and Kristinn R. Thórisson (co-founder).?
Target Language: probably best with English
added: Oct 6, 2008

Exalead.com
Claim: none
Notes: has advanced, context-sensitive options to refine a search, e.g. by selecting related terms, type of web site , content, language or file format; advances search options include search with similar terms or for phonetic representation; one can also download their exalead desktop to index and search one’s PC – which I didn’t try
Target Language: English, German
added: July 7, 2008

Factbites.com
Claim: “where results make sense”
Notes: promises to “read” the content of sites it searchs (rather than search for keywords) and seek out the ones that feature “encyclopedia-style fact-based descriptions” (but doesn’t tell how it does what it does); similarly, results pages present full statements as result preview; makes a confusing distinction between “results from the primary (high quality) database” and others (low-quality results?) though.
Target Language: seems to work in English only
added: July 7, 2008

Fazzle.com
Claim: “A Faszinating Feature Rich Search Fest”
Notes: “feature rich” in Fazzle’s context means ‘complex interface’; search operators (AND, OR, Title, etc) can be switched on/off using radio buttons; a number of tabs reading ‘null’ suggest that the interface can be personalized; the enhanced interface is even more difficult to understand
Target Language: not specified
added: July 7, 2008

Grokker
Claim: “One search. Many sources. Broad discovery. Dynamic research”
Notes: searches Yahoo! and Wikipedia; displays search results in either outline view or map view; in the outline view, both clusters and a results list are displayed; allows filtering of results by detail, date, source and domain as well as keyword search within clusters; the map view presents clusters as circles of different sizes; both maps and outlines can be exported
Target Language: English (I think)
added: July 7, 2008

hakia.com
Claim: “A new Semantic SearchPHP module for Drupal which allows for the building of search interfaces, indexes, and data synchronization using RDF stores. (http://www.openrdf.org/contrib.jsp) engine dedicated to quality”
Notes: hakia and I got off on the wrong foot when it suggested Matilda as #1 answer for my question ‘who is the queen of England?’. Turns out this was just a misunderstanding: They did present Queen Elizabeth II as their top quality, i.e. #1 search result – but I mistook their symbol for top quality results as a symbol sponsored content.
Target language: not specified, results seem better in English
added: July 7, 2008

Hoonoh.com
Claim: Tells You Who You Know Who Knows
Notes: a social seach engine that mines data from the social web (e.g. del.icio.us) and the Semantic Web (e.g. revyu.com), not sure exactly, but it seems as if Tom Heath (creator of revyu.com, member of the Linked Data initiative) is working on it; not sure either how the login works (no password required, 11-Sep-2008), but it is supposedly allowing you to filter people by proximity (Friends, Friends of Friends, etc.) and to weight results by experience, expertise and affinity scores
Target Language: none specified
added: July 7, 2008

Kartoo.com
Claim: none
Notes: a meta search engine that displays search results both as a map and as topic folders; the map is created within seconds, yet the flash-based design is a matter of taste and has zero-accessibility written all over it
Target Language: none specified
added: July 7, 2008

Lexxe
Claim: “powered by advanced natural language processingNatural Language processing (NLP) is a field of computer science and linguistics concerned with the interactions between computers and human (natural) languages. In theory, natural-language processing is a very attractive method of human-computer interaction. Natural-language understanding is ... technology”
Notes: presents both clusters and s list of search results, draws strongly on wikipeda (like PowersetSearch engine applying natural language processing to search, aiming to improve the way we find information by unlocking the meaning encoded in ordinary human language. Wikipedia is used as a knowledge basis.), but includes other sources as well, currently (July 2008) in alpha (i.e. not as mature as beta?)
Target Language: English
added: July 7, 2008

Me.Dium Social Search
Claim: “Search what the crowds are surfing”
Notes: say that it “enables users to find relevant information based on the current surfing activity of other people”; the crowds behind Me.dium are the alleged 2 million people who have downloaded the Me.dium Toolbar (July 2008; one can only guess how may of these are really using it); like Hakia and Cluuz, they are using the Yahoo! Search Boss service to accelarate and improve their service
Target Language: doesn’t seem to be relevant
added: July 7, 2008

Metaglossary.com
Claim: “Find meaning, not just links”
Notes: Promises to be now (July 08) “defining over 2,000,000 terms, phrases and acronyms!”; search results page presents key words, related terms, and a preview of definitions; in my test searches, Metaglossary offered consistently more definitions than the define: search operator in Google
Target Language: English
added: July 7, 2008

mnemo.org (Mnemomap)
Claim: none / maybe “a search engine that tries to replace the search with fun”
Notes: generates a map from the search term that shows synonms, neighbours, tags and translations (but without context, these can be confusing – ‘queen’ was translated into German as ‘Dame’ and ‘Schwuchtel’, i.e. dame and a derogatory term for homosexual males); allows users to edit (and potentially improve) search results by ‘deleting’ unwanted results from the list
Target Language: English (map and search results), German (map only)
added: July 7, 2008

Mooter.com
Claim: “The power of relevance”
Notes: breaks the process of making search relevant down into two steps: first, it presents you with a graph for your search term and asks you to choose one (!) node; then you move on to the search results; the former nodes are now visible as clusters to the left (makes you wonder why they chose to present the graph as interstitial instead of jumping to the clusters plus results list right away – because somebody built a visualization tool and was determined to use it somewhere in Mooter?)
Target Language: not specified, seems to work better with English
added: July 7, 2008

OntoSelect
Claim: “Ontology, an ontology is a formal representation of knowledge as a set of concepts within a domain, and the relationships between those concepts. It is used to reason about the entities within that domain, and may be used to describe the domain. In theory, an ontology is a "formal, explicit ... Search, Selection and Browsing”
Notes: not a semantic search engine as such, but a search tool for the semantic web community, helping them find the right ontology, multilingual labels or top labels for their projects
Target Language: Multilingual
added: July 7, 2008

Powerset.com
Claim: “A better way to search and discover information in Wikipedia articles.”
Notes: only searches Wikipedia, shows fact summaries on top of search results pages, promises to find immediate answers to (simple) questions; hype factor is high, in particular after being purchased by Microsoft.
Target Language: English
added: July 7, 2008

Pluribo.com
Claim: “Instant summaries of AmazonAmazon. com, Inc. is a US-based multinational electronic commerce company. Headquartered in Seattle, Washington, it is America's largest online retailer, with nearly three times the Internet sales revenue of the runner up, Staples, Inc. , as of January 2010. Jeff Bezos founded Amazon. com, Inc. ... user reviews.”
Notes: A rather specialized search tool: It claims to be compiling a super-summary of Amazon user reviews, so that you’d only have to read one review instead of having to dig through several dozens of them; hyped after it was discussed on Slashdot; downside: I couldn’t test it as it only works with Amazon electronics, but I couldn’t find one product within Amazon electronics that it could process (July 2008)
Target Language: English (on Amazon.com)
added: July 20, 2008

Quintura.com
Claim: “See & Find”
Notes: also calls itself a “visual find engine”; I’d recommend it to everyone who wants to create a tag cloud around a certain topic, e.g. for a presentation or blog entry, as it it creates logo enhanced tag clouds for each search term; not sure how good it is as a search engine
Target Language: not specified
added: July 7, 2008

Riya.com
Claim: “Visual search”
Notes: another visual search engine; the search index seems to be relatively small and it is not transparent where the searched files and documents are hosted (on the internet in general or actually on Riya?); allows users to search tags AND to add tags to selected items on the results page
Target Language: English (cannot handle German Umlaut)
added: July 7, 2008

Searchthetail.com
Claim:Search • Relate • Refine • Discover
Notes: Probably of appeal mainly to Search Engine Optimizers; run by Canadian company useAPI! Search: and “powered by Google” (whatever that means), it allows you to find related search terms that people have used. E.g. “Cupcakes” produces 199 related key words with English langauge settings (e.g. wedding cupcake, birthday cupcakes, cupcakes recipe, cupcakes recipes, etc), but only 10 (including “cupcakes resepti”) with Finnish language settings. Probably also good as a keyword localization tool.
Target Languages: British and American English, French, German, Spanish, Italian, Dutch, Danish, Finnish, Swedisch, Norwegian (as judged by the flags on their website), plus Arabic, Japanese, Chinese and Vietnamese (as judged by the tabs on the bottom)
added: Oct 6, 2008

semager.de
Claim: “semantisch suchen” (“searching semantically”)
Notes: The related terms search seems useful, and so does the service “Semantic Business” which includes (but is not limited to) a Keyword API, Brands API, TagCloud API and TextCloud API. The feature “Typos/Tippfehler” might be useful for the definition of hidden labels in a thesaurusA thesaurus is a book that lists words grouped together according to similarity of meaning, in contrast to a dictionary, which contains definitions and pronunciations. The largest thesaurus in the world is the Historical Thesaurus of the Oxford English Dictionary, which contains more than ....
Target Language: German, English; currently (July 2008) working on Spanish Semantics
added: July 7, 2008

Swoogle
Claim: “Semantic Web Search”
Notes: a search engine for the semantic community rather than a semantic search engine; searches (for) semantic web ontologies, documents and terms; search results are also available in RDF
Target Language: not specified

Trexy.com
Claim: “Blaze search trails”
Notes: a social search engine with modest capabilities – allows you to follow other people’s search trails, presumably by registering the links that people clicked in their search results; the search results are, however, poorly displayed: my search for “queen” produced five links including “coming soon” and “untitled” and not even a preview of the URL; also only 12 people had searched for “Queen” before – I guess only few search terms reach threshold value on Trexy
Target Language: dominated by English searches
added: July 7, 2008

Ujiko.com
Claim: none – I’d suggest “Beam me away, Uji”"
Notes: searches 6 Million web pages, but its selling point is the sci-fi interface; search results are displayed in a circular interface, with what could be keywords or tags appearing in the middle; clicking on any of these terms refines the search; flash overload
Target Language: not specifed (certainly German, French and English)
added: July 7, 2008

virel.de
Claim: Make yourself visible
Notes: A microformatsCentral resource of the microformats community (http://microformats.org). search engine, created by a small German company; it trakcs microformatsA microformat (sometimes abbreviated μF) is a web-based approach to semantic markup which seeks to re-use existing HTML/XHTML tags to convey metadata and other attributes in web pages and other contexts that support (X)HTML, such as RSS. This approach allows software to process information ... on the web, but also accepts submissions of microformats providers; allows to search for contacts (hcard) and events (hcalendar)
Target Language: not specifed/relevant; has German and English interface
added: July 7, 2008

And:

The Big ones: Glimpses of the Semantic Web
I don’t really dare to give Yahoo and Google their own place within this list, but let’s at least mention their current efforts:

Yahoo
In March 2008, Yahoo announced plans to gradually support a number of microformats, including hCard, hCalendar, hReview, hAtom, and XFNSimple way to represent human relationships using hyperlinks. (http://www.gmpg.org/xfn/), to support vocabulary components from Dublin CoreSpecification of all metadata terms maintained by the Dublin Core Metadata Initiative, including properties, vocabulary encoding schemes, syntax encoding schemes, and classes. (http://dublincore.org/documents/dcmi-terms/), Creative Commons, FOAFhttp://www.foaf-project.org/, GeoRSS, MediaRSS and to support RDFa and eRDF markup to embed these into existing HTML pages. They also announced their support for the OpenSearch specification. Furthermore, the Yahoo! Search Boss webservice might help in particular niche search engines to improve their services – ReadWriteWeb as an interesting article about it.
added: July 7, 2008

Google
In terms of relationship finding, Google sets is rather interesting: Enter appleApple Inc. is an American multinational corporation that designs and manufactures consumer electronics, computer software, and commercial servers. The company's best-known hardware products include Macintosh computers, the iPod, the iPhone and the iPad. Apple software includes the Mac OS X ... and pear, and it will suggest cherry, sweet and chocolate. Enter apple and PC, and it will suggest mac, windows and microsoft.
added: July 7, 2008