April 16, 2019

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

       Re: Fastly, Inc.
           Amendment No. 1 to Draft Registration Statement on Form S-1
           Submitted April 4, 2019
           CIK No. 0001517413

Dear Mr. Bergman:

      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. Unless otherwise noted, where a prior comment is referred to it
refers to our letter
dated March 13, 2019.

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

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

1.     We note that your DBNER decreased from 147.3% in 2017 to 132.0% in 2018.
Please
       revise to disclose an explanation for the decrease and your expectations
regarding future
       trends in this metric, if any. We refer you to Item 303(a)(3) of
Regulation S-K for
       additional guidance.
 Artur Bergman
FirstName LastNameArtur Bergman
Fastly, Inc.
Comapany NameFastly, Inc.
April 16, 2019
April 2 2019 Page 2
Page 16,
FirstName LastName
Critical Accounting Policies and Estimates
Common Stock Valuation, page 78

2.       We note your response to prior comment 7 and have the following
comments:

             Please explain how the June 2018 equity financing of $40 million
of Series F Preferred
             Stock for $5.1123 per share was considered in your June 29, 2018
valuation of
             common stock;
             Describe in further detail the "IPO scenario" valuation method
used in your September
             and December 2018 valuations;
             Explain how the fair values of your common stock as determined in
your 2018
             valuations reconcile to the fair value of common stock disclosed
on page F-28;
             Revise your subsequent events note on page F-34 to disclose the
expected financial
             impact of the stock options granted in February 2019 pursuant to
ASC 855-10-50-2(b);
             and
             Continue to provide us with an analysis of fluctuations in the
fair value of your
             common stock through the determination of your IPO price range.
        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,

                                                              Division of
Corporation Finance
                                                              Office of
Information Technologies
                                                              and Services
cc:      Seth Gottlieb