We developed a Twitter app to suggest users to mention in a tweet in order to maximise the spread of an information. Users that are popular, active on Twitter and interested in the content of the tweet are targeted. The problem is mapped to the knapsack problem, the length of the screen name of a user being an important variable. Collected data (who retweets among the suggested users and features of these users) will be used to improve the app and theory/models of information spread on Online Social Networks. The application is available at: http://bit.ly/1BKZURE