The Dropbox API for Android or iOS devices [25,26] is a RESTful API that uses the OAuth protocol to allow an application to access a folder in the user’s Dropbox area across the Web. To use the API, a developer must create an online Dropbox application linked to the developer’s Dropbox account. This generates an “app key” and “secret key” used to authenticate the application when Dropbox seeks authorization from the user to allow the application to access the user’s area. In development, a Dropbox application can be tested by up to five users. After the application has been approved by Dropbox, multiple users can use the service.