 After its public release in February 2014, the tool grew at a weekly rate of 5 to 10 percent, with more than 120,000 daily users registered in the first week of August.In early 2014, the data for Slack's first six-month usage period showed that nearly 16,000 users were registered without any advertising.That same year, Butterfield secured an office for Slack employees in San Francisco, and was expected to commence recruitment during the second half of the year.