For over a decade, Dropbox has been a staple of the cloud storage industry, despite hard competition from larger players like Google and Microsoft. All that time, the company has remained private, but that's about to change. Dropbox filed to raise $500 million in an initial public offering (IPO) yesterday, revealing previously-secret details about the company.

The filing revealed Dropbox had $1.11 billion of revenue in 2017, up 31% from 2016. There are over 500 million registered users, with 100 million just from 2017 alone. More than 11 million of those users pay for a premium plan. The filing also shows Dropbox has been bleeding money for years, but it's getting closer to becoming profitable. The company lost $210.2 million in 2016, but only $111.7 million in 2017.

Another interesting part of the filing is that normal users buying subscriptions, not enterprise sales, make up for over 90% of the company's revenue. Dropbox plans to use proceeds from the IPO to upgrade more users to subscription plans and improve integration of third party software (like how Dropbox is closely integrated with Office 365).