Exhibit 23.1 CONSENT OF INDEPENDENT ACCOUNTANTS We consent to the inclusion of our report dated March 31, 2000, with respect to the consolidated balance sheet of AdForce, Inc. as of December 31, 1999 and the related consolidated statements of operations, common stockholders' equity (deficit) and cash flows for the year ended December 31, 1999. /s/ KPMG LLP San Francisco, California August 16, 2000