SAN FRANCISCO — Slack, the workplace messaging start-up, disclosed the details of its business in an offering prospectus on Friday as it joined the parade of tech companies that plan to publicly list their shares this year.

Sharing its financial results widely for the first time, Slack said it had collected $400.6 million in revenue in its latest fiscal year, which ended Jan. 31. That was nearly double what it had generated in the previous fiscal year. It lost $140.7 million in the latest fiscal year, narrowing its losses from $180.9 million the year before.

The company had 88,000 paying customers at the end of the most recent fiscal year, up almost 50 percent from the previous year. Of those customers, 575 paid more than $100,000 for their subscriptions, contributing about 40 percent of the company’s revenue.

Friday’s filing shed more light on Slack, which has grown out of a video game company into an increasingly common way for workers to communicate. Its software is meant to be a replacement for email — but it also lets colleagues chat and share files, among other tasks.