September 19, 2018

Scott Behrens
Chief Financial Officer
ACI WORLDWIDE, INC.
3520 Kraft Rd., Suite 300
Naples, FL 34105

       Re: ACI WORLDWIDE, INC.
           Form 10-K for the Fiscal Year Ended December 31, 2017
           Filed February 27, 2018
           Form 10-Q for the Quarterly Period Ended March 31, 2018
           Filed May 10, 2018
           File No. 000-25346

Dear Mr. Behrens:

       We have limited our review of your filings to the financial statements
and related
disclosures 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 these comments within ten business days by providing
the requested
information or advise us as soon as possible when you will respond. If you do
not believe our
comments apply to your facts and circumstances, please tell us why in your
response.

       After reviewing your response to these comments, we may have additional
comments.

Form 10-Q for the Quarterly Period ended March 31, 2018

Note 2. Revenue
Software as a Service ("SaaS") and Platform as a Service ("PaaS") Arrangements,
page 9

1.    On page 33 you indicate that SaaS and PaaS costs include payment card
interchange and
      processing fees and are included in cost of revenue. Please tell us how
you calculate
      revenue in arrangements related to these fees, whether it includes
amounts paid to third
      parties and how you concluded such amounts should be reflected on a gross
basis in
      revenue and cost of revenue. Reference ASC 606-10-55-36 through 39A.
 Scott Behrens
ACI WORLDWIDE, INC.
September 19, 2018
Page 2
2.       You disclose that your SaaS-based and PaaS-based arrangements
represent a single
         promise to provide continuous access, a stand-ready performance
obligation, to your
         software solutions and its processing capabilities. You also indicate
that fixed
         consideration under these arrangements may relate to a material right.
Please tell us, and
         revise your disclosures to clarify, whether the material right is a
separate performance
         obligation and if and how you have allocated consideration to this
promise. Reference
         ASC 606-10-55-41.
Significant Judgments, page 11

3.       You disclose that the selling prices of your software licenses are
highly variable and you
         use the residual approach to estimate standalone selling price. Please
provide a
         comprehensive, quantitative discussion of such variability to support
your conclusion.
         Reference ASC 606-10-32-34.
4.       You disclose that you apply judgment in determining the term of an
arrangement when
         early termination rights are provided to the customer. Please help us
better understand
         how you have analyzed termination provisions and the resulting impact
on contractual
         terms. In this regard, tell us if your arrangements contain
termination penalties.
       In closing, 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.

      You may contact Ryan Rohn, Staff Accountant, at (202) 551-3739 or Stephen
Krikorian,
Accounting Branch Chief, at (202) 551-3488 with any questions.



                                                               Sincerely,
FirstName LastNameScott Behrens
                                                               Division of
Corporation Finance
Comapany NameACI WORLDWIDE, INC.
                                                               Office of
Information Technologies
September 19, 2018 Page 2                                      and Services
FirstName LastName