Slack (WORK) S-1/A IPO registration (amended)

Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

The Board of Directors

Slack Technologies, Inc.:

We consent to the use of our report included herein and to the reference to our firm under the heading “Experts” in the prospectus.

/s/ KPMG LLP

San Francisco, California

May 13, 2019