EXHIBIT 99.1


                     CERTIFICATE OF CHIEF EXECUTIVE OFFICER
                           AND CHIEF FINANCIAL OFFICER


     This Certificate is being delivered pursuant to the requirements of Section
1350 of Chapter 63 (Mail Fraud) of Title 18 (Crimes and Criminal Procedures) of
the United States Code and shall not be relied on by any person for any other
purpose.

     The undersigned, who are the Chief Executive Officer and Chief Financial
Officer, respectively, of S1 Corporation (the "Company"), hereby each certify as
follows:

     To the knowledge of the undersigned, the Quarterly Report on Form 10-Q of
the Company (the "Report"), which accompanies this Certificate, fully complies
with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act
of 1934, and all information contained in the Report fairly presents, in all
material respects, the financial condition and results of operations of the
Company.

     Dated this 14th day of August, 2002.



                                  /s/ Jaime W. Ellertson
                                  ---------------------------------------------
                                  Jaime W. Ellertson, Chief Executive Officer



                                  /s/ Matthew Hale
                                  ---------------------------------------------
                                  Matthew Hale, Chief Financial Officer