New York (CNN Business) Five years ago, Slack officially launched out of the ashes of a failed gaming project. Now the company is worth more than $20 billion.

Slack, the workplace communication tool popular in tech and media circles, began trading on the New York Stock Exchange on Thursday, making it the latest tech unicorn to race to Wall Street this year. But Slack took a more unconventional approach to going public.

Spotify SPOT The company chose to list its existing shares directly on the stock exchange rather than raising money by issuing new shares to be sold to public investors., another tech company, took the same approach when it went public last year

Slack opened at $38.50 a share on Thursday, and ended the day slightly higher at $38.62 a share, a nearly 50% increase from its $26 reference price — not to be confused with an IPO price — set on the eve of its market debut. At its closing price, Slack had a market value of roughly $23 billion.

"There was definitely quite a lot of debate for awhile because it isn't the traditional route," Cal Henderson, Slack's cofounder and CTO, told CNN Business in an interview on Thursday about the decision to do a direct listing. "But we didn't have a need to raise capital. That was the biggest driver."