April 12, 2019

Stewart Butterfield
Chief Executive Officer
Slack Technologies, Inc.
500 Howard Street
San Francisco, CA 94105

       Re: Slack Technologies, Inc.
           Amendment No. 2 to
           Draft Registration Statement on Form S-1
           Submitted April 4, 2019
           CIK No. 0001764925

Dear Mr. Butterfield:

      We have reviewed your amended draft registration statement and have the
following
comments. In some of our comments, we may ask you to provide us with
information so we
may better understand your disclosure.

       Please respond to this letter by providing the requested information and
either submitting
an amended draft registration statement or publicly filing your registration
statement on
EDGAR. If you do not believe our comments apply to your facts and circumstances
or do not
believe an amendment is appropriate, please tell us why in your response.

      After reviewing the information you provide in response to these comments
and your
amended draft registration statement or filed registration statement, we may
have additional
comments.

Amendment No. 2 to Draft Registration Statement on Form S-1

RSU Sales, page 57

1.     In order to estimate the approximate number of shares to be sold at the
opening of trading
       for the purpose of funding personal tax withholding and remittance
obligations, you will
       have to estimate the sale price. Tell us who will be responsible for
this calculation, and to
       whom it will be communicated to prior to the opening of trading.
 Stewart Butterfield
FirstName LastNameStewart Butterfield
Slack Technologies, Inc.
Comapany NameSlack Technologies, Inc.
April 12, 2019
Page 12,
April 2 2019 Page 2
FirstName LastName
Management's Discussion and Analysis of Financial Condition and Results of
Operations
Results of Operations, page 75

2.       We note your response to comment 7 and your acknowledgement that
management
         measures and reviews upgrades of organizations from your free to paid
subscription
         plans. Please disclose the percentage of the Company's revenue derived
         from organizations on your free subscription plan that converted to a
Paid Customer for
         all of the periods presented in your MD&A. Also disclose the
percentage of revenue
         generated from your Paid Customers >$100,000 for each period.
Experts, page 168

3.       Please revise to also make reference to the financial statements as of
and for the period
         ended January 31, 2019.
Consolidated Financial Statements
Note 14. Subsequent Events, page F-36

4.       You disclose on page 161 that you sold approximately 2.5 million Class
B shares at prices
         ranging from $21-$26 per share during February and March 2019. We also
note your
         disclosure on page F-36 that you granted stock options to purchase 3.6
million Class B
         shares at an exercise price of $10.56 per share in addition to 15.7
million RSUs and
         505,000 RSAs. Please explain to us how you determined the fair value
of the Class B
         common stock underlying all equity related issuances during the last
twelve months and
         the reasons for any differences between those values compared to
recent valuations of
         your Class B common stock in connection with private sale transactions
leading up to the
         direct listing. This information will help facilitate our review of
your accounting for
         equity issuances including stock compensation.
        You may contact Lisa Etheredge, Staff Accountant, at (202) 551-3424 or
Robert S.
Littlepage, Accounting Branch Chief, at (202) 551-3361 if you have questions
regarding
comments on the financial statements and related matters. Please contact Joshua
Shainess,
Attorney-Adviser, at (202) 551-7951 or Larry Spirgel, Assistant Director, at
(202) 551-3810 with
any other questions.



                                                               Sincerely,

                                                               Division of
Corporation Finance
                                                               Office of
Telecommunications