EXHIBIT 23.1 INDEPENDENT AUDITORS' CONSENT To the Board of Directors and Stockholders of Aspen Technology, Inc.: We consent to the incorporation by reference in Registration Statement Nos. 333-11651, 333-21593, 333-42536, 333-42358, 333-42540, 333-71872, 333-71874, and 333-80225 on Form S-8 and Registration Statement Nos. 333-89710, and 333-90066 on Form S-3 of Aspen Technology, Inc. of our report dated August 13, 2002, appearing in this Annual Report on Form 10-K of Aspen Technology, Inc. for the year ended June 30, 2002. /s/ DELOITTE & TOUCHE LLP Boston, Massachusetts September 25, 2002