Twitter is believed to be in advanced talks to buy TweetDeck for around $50m (£30.7m). TweetDeck – a third-party app designed to integrate with Twitter – filters conversations based on keywords and messages, while allowing users to write tweets in excess of the default 140 character limit. TweetDeck has at least 15 employees, the majority of which are located in the UK. Twitter and TweetDeck have worked closely together in the past, according to the Wall Street Journal which originally reported the talks. A Twitter spokesman declined to comment.