<PAGE>
EXHIBIT 23.1
CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS
We consent to the reference to our firm under the caption "Experts" in the
Registration Statement on Form S-3 of Portal Software, Inc. for the registration
of 7,500,000 shares of its common stock and to the incorporation by reference
therein of our report dated February 16, 2000, except for paragraph 4 of Note 4
as to which the date is March 13, 2000, with respect to the consolidated
financial statements of Portal Software, Inc. included in its Annual Report on
Form 10-K for the year ended January 31, 2000, filed with the Securities and
Exchange Commission.
/s/ Ernst & Young LLP
Palo Alto, California
November 9, 2000
