SAN FRANCISCO (REUTERS) - Slack Technologies Inc said on Monday (June 10) it expects fiscal 2020 revenue to grow as much as 50 per cent but the owner of the workplace instant messaging app anticipates a loss for the year, ahead of its listing this month.

Slack is one of the most high-profile companies left to list their shares in 2019, following initial public offerings of Pinterest Inc, Zoom Video Communications and Beyond Meat.

However, the struggles of ride-hailing company Uber Technologies Inc and its smaller rival Lyft Inc , the two biggest IPOs so far this year, have cast a pall over new tech listings.

San Francisco-based Slack, whose customers include Electronic Arts Inc, Nordstrom Inc and Ford Motor Co, said it was seeing strong user retention and engagement rates, ahead of its plans to go public via a direct listing instead of an IPO on June 20.

Slack said it continued to see 'broad adaption' across a variety of industries and geographies in the first quarter, with user retention and engagement rates rising.

"Users, (who) are paid customers spend more than 9 hours a day connected to Slack, and 90 minutes actively using the platform on a typical workday," Chief Executive Officer Stewart Butterfield said on a conference call.

The company, which competes with platforms such as Microsoft Teams - a free chat add-on for Microsoft's Office365 users - forecast fiscal 2020 revenue in the range of US$590 million (S$805 million) to US$600 million, representing growth of 47 per cent to 50 per cent over the previous year.

Slack expects an adjusted operating loss between US$192 million and US$182 million and forecast full-year billings of US$725 million to US$745 million, up 40 per cent to 44 per cent from a year earlier.

Slack ended the first quarter with 95,000 paid customers and posted 67 per cent growth in quarterly revenue at US$134.8 million.

The company reported an operating loss of US$33.8 million for the quarter, compared with a US$20.2 million loss a year earlier.