Clarifai, an A.I. start-up, built a face database with images from OkCupid, due to common founders in both companies. 2019 alleged credential stuffing incident A February 2019 report alleged that many users reported lost access to their accounts in a manner consistent with either a data breach or a widespread "credential stuffing" incident. "Credential stuffing" describes using passwords stolen from one service (like another dating site) to attack another service, on the assumption that many people will reuse passwords across websites. OkCupid denied any data breach or system errors. Overview OkCupid claimed 3.5 million active users as of September 2010. According to Compete.com, the website attracted 1.3 million unique visitors in February 2011. Any adult may join the site and all users may communicate with others via private messages or an instant messaging "chat" function. OkCupid was the first major dating site to offer unlimited messaging free of charge, although this was limited in late 2017 when OkCupid's official blog announced the site is "getting rid of open-messaging" and making sent messages invisible to the sender until the recipient interacts by either matching or replying to the message. Recipients will be able to read their messages (from people within their preference settings that have not already been passed) before a match by way of an "Intro" tab. All messages under that tab are blurry and must be processed one at a time. The term "A-List" to describe paying members was updated to "Basic" and "Premium" services. People who pay for access will see no advertising and will have an unlimited ability to "Like" other profiles. Those paying for Premium have the additional option of being able to see the list of names for people who have liked them. In early May 2020, OKCupid removed the match search function for some users, including all those in Australia and including A-list subscribers. Following complaints, it has had to reimburse Australian users but, regardless of past complaints, implemented the removal for all users in July 2020. Amid the coronavirus pandemic, OkCupid reported a 23.4% decrease in monthly active users in the final quarter of 2020. Matching To generate matches, OkCupid applies data generated by users' activities on the site, as well as their answers to questions. Over 4000 questions can be answered and the company suggest answering between 50 and 100 to get started. When answering a question, a user indicates their own