Exhibit 23.1 CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS We consent to the incorporation by reference in the Registration Statements (Form S-8 No. 333-59959, 333-73015) pertaining to the 1998 Equity Incentive Plan, 1998 Employee Stock Purchase Plan and 1998 Non-Employee Directors Option Plan of Actuate Corporation of our report dated January 12, 2000, with respect to the consolidated financial statements of Actuate Corporation included in the Annual Report (Form 10-K) for the year ended December 31, 1999. /s/ Ernst & Young LLP Palo Alto, California March 27, 2000