Exhibit 32.1


                            CERTIFICATION PURSUANT TO

                             18 U.S.C. SECTION 1350

                       AS ADOPTED PURSUANT TO SECTION 906

                        OF THE SARBANES-OXLEY ACT OF 2002


     I, Umang  Gupta,  Chief  Executive  Officer  and  Chairman  of the Board of
Keynote Systems, Inc. (the "Company"),  do hereby certify,  pursuant to 18 U.S.C
Section 1350, as adopted  pursuant to Section 906 of the  Sarbanes-Oxley  Act of
2002, that, to my knowledge:


     o    the Annual  Report on Form  10-K/A of the  Company  for the year ended
          September  30,  2006,  as filed  with the  Securities  and o  Exchange
          Commission on December 13, 2006 (the  "Report"),  fully  complies with
          the requirements of Section 13(a) or 15(d) of the Securities  Exchange
          Act of 1934; and

     o    the  information  contained  in the  Report  fairly  presents,  in all
          material respects,  the financial  condition and results of operations
          of the Company for the periods presented therein.


Date: March 12, 2007


        /s/ UMANG GUPTA
- ------------------------------------------------
            Umang Gupta

     Chief Executive Officer and
        Chairman of the Board
     (Principal Executive Officer)


A signed original of this written statement required by Section 906 has been
provided to Keynote Systems, Inc. and will be retained by it and furnished to
the Securities and Exchange Commission or its staff upon request.