More than 83% of the organizations using Slack do so without paying the business messaging company, but the minority who do have helped create a business that saw revenue jump 82% to more than $400 million in its most recent fiscal year.

Those were among the details in Slack’s much-anticipated filing with securities regulators for a direct listing of its shares on Friday morning. The document provided a window into a company that has touted the grass roots growth of its communications tools inside companies, but is still spending heavily on sales and marketing—by far, its biggest expense—to fuel growth. The spending has contributed to losses in the hundreds of millions of dollars at the company for several years, though they have decreased as a percentage of revenue over time.