2/24/2018 S-1 Table of Contents revenue. We estimate that approximately 300 million of our registered users have characteristics—including specific email domains, devices, and geographies—that make them more likely than other registered users to pay over time. Substantially all of our paying users share at least one of these characteristics. We reach our users through in­product notifications on our website and across hundreds of millions of actively connected devices, without any external marketing spend. We define an actively connected device as a desktop, laptop, phone, or tablet on which our app has been installed, and from which our app has been launched, and made a request to our servers at least once in the most recent quarter. Upgrade our paying users We offer a range of paid subscription plans, from Plus and Professional for individuals to Standard, Advanced, and Enterprise for teams. We analyze usage patterns within our network and run hundreds of targeted marketing campaigns to encourage paying users to upgrade their plans. For example, we prompt individual subscribers who collaborate with others on Dropbox to purchase our Standard or Advanced plans for a better team experience. In 2017, over 40% of new Dropbox Business teams included a member who was previously a subscriber to one of our individual paid plans. We believe that a large majority of individual customers use Dropbox for work, which creates an opportunity to significantly increase conversion to Dropbox Business team offerings over time. Apply insights to build new product experiences As our community of users grows, we gain more insight into their needs and pain points. We translate these insights into new product experiences that support the entire content lifecycle. For example, we learned through analytics and research that our users often work with many different types of content. As a result, we added the ability to embed rich media in Paper so they can pull everything together in one place—from InVision graphics and Google slides to Spotify tracks and Vimeo clips. Expand our ecosystem Our open and thriving ecosystem fosters deeper relationships with our users and makes Dropbox more valuable to them over time. The scale and reach of our platform is enhanced by a number of third­party applications, developers, and technology partners. As of December 31, 2017, Dropbox was receiving over 50 billion API calls per month, and more than 500,000 developers had registered and built applications on our platform. Our Market Opportunity Over the past decade, Dropbox has pioneered the worldwide adoption of file sync and share software. We’ve since expanded our capabilities and introduced new product experiences to help our users get work done. For the second consecutive year, Gartner has named Dropbox a leader in their Magic Quadrant for Content Collaboration Platforms. Our addressable market includes collaborative applications, content management, project and portfolio management, and public cloud storage. IDC estimates that investment in these categories will total more than $50 billion in 2019. As one of the few large­scale collaboration platforms that serves customers of all sizes, we also have an opportunity to reach a broad population of independent knowledge and creative workers. We believe that this market hasn’t traditionally been included in IT spending estimates. Our Capabilities Dropbox is a digital workspace where individuals and teams can create content, access it from anywhere, and share it with collaborators. The power of our platform lies in the breadth of our capabilities and the diverse 95 https://www.sec.gov/Archives/edgar/data/1467623/000119312518055809/d451946ds1.htm 103/235