<TABLE> <S> <C>
<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM ARIBA INC.'S
QUARTERLY REPORT ON FORM 10-Q FOR THE PERIOD ENDED JUNE 30, 2000 AND IS
QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
<S> <C>
<PERIOD-TYPE> 9-MOS
<FISCAL-YEAR-END> SEP-30-2000
<PERIOD-START> OCT-01-1999
<PERIOD-END> JUN-30-2000
<CASH> 183,747
<SECURITIES> 154,408
<RECEIVABLES> 48,634
<ALLOWANCES> (4,665)
<INVENTORY> 0
<CURRENT-ASSETS> 302,377
<PP&E> 38,343
<DEPRECIATION> (6,250)
<TOTAL-ASSETS> 3,570,970
<CURRENT-LIABILITIES> 232,247
<BONDS> 0
0
0
<COMMON> 476
<OTHER-SE> 3,337,714
<TOTAL-LIABILITY-AND-EQUITY> 3,570,970
<SALES> 95,545
<TOTAL-REVENUES> 144,186
<CGS> 5,358
<TOTAL-COSTS> 23,882
<OTHER-EXPENSES> 582,879
<LOSS-PROVISION> 1,527
<INTEREST-EXPENSE> 161
<INCOME-PRETAX> (452,558)
<INCOME-TAX> 875
<INCOME-CONTINUING> (453,433)
<DISCONTINUED> 0
<EXTRAORDINARY> 0
<CHANGES> 0
<NET-INCOME> (453,433)
<EPS-BASIC> (2.46)
<EPS-DILUTED> (2.46)
</TABLE>