2/24/2018 S-1 Table of Contents Smart Sync. With Smart Sync, users can access all of their content natively on their computers without taking up storage space on their local hard drives. We intelligently sync files to a user’s computer as they need them, and users can control which files or folders are always synced locally. With Smart Sync, files that are only stored in the cloud appear in the local file system and can be opened directly from Windows File Explorer or Mac Finder, instead of having to navigate to our web interface. Smart Sync is available to Dropbox Professional subscribers and Dropbox Business teams. Version history. As paying users work on files, our servers keep snapshots of all their changes. Users can see a file’s complete version history so they can reference and retrieve older versions if needed. Version histories are kept between 30 to 120 days for paying users, depending on subscription plan. Third­party ecosystem. Our open and thriving ecosystem fosters deeper relationships with our users and developers. Developers can build applications that connect to Dropbox through our DBX Developer Platform. For example, email apps can plug into Dropbox to send attachments or shared links, and note­taking apps can allow users to save to Dropbox so they can open their notes on another device. As of December 31, 2017, Dropbox was receiving over 50 billion API calls per month and over 500,000 developers had registered and built applications on our platform. In addition, more than 75% of Dropbox Business teams have linked to one or more third­party applications. Share Folders. There are three types of folders in Dropbox: private, shared, and team folders. A private folder allows an individual to sync files between devices. A shared folder allows users to quickly and easily start a project space for group collaboration. A team folder, which is only available for Dropbox Business teams, is a central, administrator­managed hub where they can store and collaborate on content. 100 https://www.sec.gov/Archives/edgar/data/1467623/000119312518055809/d451946ds1.htm 108/235