WOT Services, Ltd is a Finnish company that runs the partly crowdsourced Internet website reputation rating tool Web of Trust (WOT). The installed WOT browser add-on shows its users the reputations of websites, which are calculated through a combination of user ratings and data from other sources.
WOT was founded in 2006 by Sami Tolvanen and Timo Ala-Kleemola, who wrote the WOT software as post-graduates at the Tampere University of Technology in Finland. They launched the service officially in 2007, with serial entrepreneur and angel investor Esa Suurio as CEO. In November 2009 Suurio moved on to his next endeavor.
The WOT browser add-on does two things: (1) it sends user ratings to the WOT site, and (2) it displays the computed results via color-coded icons in the user's browser tool-bar and next to external links on the pages of leading search engines, email services and social network sites. The add-on source code is public.
The program software at WOT headquarters is not public. According to the company information it is designed to compute the measure of trust the rating users have in websites, enhanced with data from a number of third-party sources. The user rating system claims to be meritocratic; the weight of ratings are algorithmically calculated for each user individually.
To generate revenue WOT licenses the use of its reputation database to other businesses.
On December 7, 2010, ten companies all associated to Ayman El-Difrawi aka Alec Difrawi filed a lawsuit in Florida against WOT Services for defamation, violating rights, conspiracy and manipulating algorithms, among other claims, demanding WOT to remove ratings and comments for their numerous websites. On December 8, 2011, the case was dismissed with prejudice. 
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