Is Dropbox secure for accountants? Dropbox is a cloud-based service that allows users to store files online. With a free plan and a paid plan for users whose storage exceeds 2 G.B., users can share files and folders without needing to send large attachments. A user only needs to share a link to specific files, saving them from the need to send e-mail attachments. It also offers a backup, meaning that if a device such as a laptop or mobile phone is lost, you still have access to your files.