Slack confidentially filed to go public, according to a press release published Monday.

Slack, a provider of chat and direct messaging services for businesses, is one of a number of tech IPOs expected in 2019, including Uber, Lyft and Airbnb. The company hired Goldman Sachs to lead its initial public offering as an underwriter, Reuters reported in December, saying Slack was seeking a valuation of more than $10 billion in its IPO. Slack has raised about $1 billion so far, according to Crunchbase.

Slack is planning to pursue a direct listing, sources told The Wall Street Journal, according to a report from last month. If Slack follows through with the direct listing, that would make it the second big technology company to do so, according to the Journal, following Spotify's lead.

Slack reportedly has plenty of cash on hand to pursue the direct listing route. According to The Information, Slack had about $900 million in cash on its balance sheet as of October 2018. For the year ended in January 2018, Slack had revenue of $221 million, The Information reported based on early 2018 documents.

Here is the full release from Slack:

Slack Technologies, Inc. today announced that it has confidentially submitted a draft registration statement on Form S-1 with the Securities and Exchange Commission (the "SEC") relating to the proposed public listing of its Class A common stock. The public listing is expected to take place after the SEC completes its review process, subject to market and other conditions. This press release does not constitute an offer to sell or the solicitation of an offer to buy any securities. Any offers, solicitations or offers to buy, or any sales of securities will be made in accordance with the registration requirements of the Securities Act of 1933, as amended ("Securities Act"). This announcement is being issued in accordance with Rule 135 under the Securities Act.

Disclosure: Comcast Ventures, the venture arm of Comcast, is an investor in Slack. Comcast owns CNBC parent company NBCUniversal.

Watch: Wide variation between potential tech IPOs in 2019, says The Information's Jessica Lessin