April 24, 2019

Artur Bergman
Chief Executive Officer
Fastly, Inc.
475 Brannan Street, Suite 300
San Francisco, CA 94107

       Re: Fastly, Inc.
           Registration Statement on Form S-1
           Filed April 19, 2019
           File No. 333-230953

Dear Mr. Bergman:

       We have reviewed your 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 amending your registration statement
and providing the
requested information. 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 any amendment to your registration statement and the
information you
provide in response to these comments, we may have additional comments. Unless
we note
otherwise, our references to prior comments are to comments in our April 16,
2019 letter.

Registration Statement on Form S-1 filed April 19, 2019

Management's Discussion and Analysis of Financial Conditions and Results of
Operations
Key Business Metrics
Dollar-Based Net Expansion Rate, page 68

1.     In your revised disclosure you state that customers tend to increase
their usage of your
       platform in their second year, which is typically followed by more
modest increases in
       usage, if any, in ensuing years. Please revise to explain in further
detail how this tendency
       specifically impacted your DBNER in 2017 and 2018, such as the numbers
of customers
       used in the 2016 and 2017 base period computations. In addition, please
address why
       your customer numbers are growing in 2018 over 2017, while DBNER for
2018 is falling
       from the 2017 DBNER.
 Artur Bergman
Fastly, Inc.
April 24, 2019
Page 2
Critical Accounting Policies and Estimates
Common Stock Valuation , page 81

2.    In your response to prior comment 2 you noted differences in the sets of
comparable
      companies, as well as selections of revenue multiples, used by the lead
underwriters and
      your third-party valuation firm. Please provide us with a complete
analysis of the
      comparable companies and revenue multiples used in the February 28, 2019
valuation and
      in the determination of your preliminary IPO price range.
        We remind you that the company and its management are responsible for
the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action
or absence of
action by the staff.

       Refer to Rules 460 and 461 regarding requests for acceleration. Please
allow adequate
time for us to review any amendment prior to the requested effective date of
the registration
statement.

       You may contact David Edgar, Staff Accountant, at (202) 551-3459 or
Craig
Wilson, Senior Assistant Chief Accountant, at (202) 551-3226 if you have
questions regarding
comments on the financial statements and related matters. Please contact Jeff
Kauten, Staff
Attorney, at (202) 551-3447 or Jan Woo, Legal Branch Chief, at (202) 551-3453
with any other
questions.



                                                           Sincerely,

FirstName LastNameArtur Bergman                            Division of
Corporation Finance
                                                           Office of
Information Technologies
Comapany NameFastly, Inc.
                                                           and Services
April 24, 2019 Page 2
cc:       Seth Gottlieb
FirstName LastName