A new, Los Angeles-based startup, MediaKits, says it has launched a new platform aimed at helping influencers, musicians, and athletes manage their brands. The company said its platform lets its users create their own custom media kits online. The startup was founded by Kieran O'Brien and Casey Adams. The startup says it plugs into the APIs of such social platforms as Facebook, Instagram, YouTube, and Twitter, letting its customers pull real-time data on numbers of followers, engagement rates, audience demographics, songs downloaded, and other inforation to help influencers position themselves to attract potential advertisers or sponsors. The company said a basic version of its software is free, with customized kits at $19 per month.