Atlassian co-founder Mike Cannon-Brookes describes Trello as a simple online application. But simple doesn't have to mean cheap: His company just agreed to acquire the web-based project management app for $425 million—a ridiculous-sounding amount of money that may well be worth paying. Despite being only the fourth-most popular project management tool according to Project Management Zone, Trello was the fastest growing in 2016 increasing from 4.5 million users in 2014 to over 19 million in 2016.
