QuickLinks -- Click here to rapidly navigate through this document

Exhibit 10.1

TWELFTH LOAN MODIFICATION AGREEMENT

        This Twelfth Loan Modification Agreement (this "Loan Modification
Agreement") is entered into on January 12, 2007 by and between SILICON VALLEY
BANK, a California chartered bank, with its principal place of business at
3003 Tasman Drive, Santa Clara, California 95054 and with a loan production
office located at One Newton Executive Park, Suite 200, 2221 Washington Street,
Newton, Massachusetts 02462 ("Bank") and ASPEN TECHNOLOGY, INC., a Delaware
corporation with offices at Ten Canal Park, Cambridge, Massachusetts 02141 for
itself and as successor by merger with ASPENTECH, INC., a Texas corporation with
offices at Ten Canal Park, Cambridge, Massachusetts 02141 ("Borrower").

1.DESCRIPTION OF EXISTING INDEBTEDNESS AND OBLIGATIONS.    Among other
indebtedness and obligations which may be owing by Borrower to Bank, Borrower is
indebted to Bank pursuant to a loan arrangement dated as of January 30, 2003,
evidenced by, among other documents, a certain Loan and Security Agreement dated
as of January 30, 2003 between Borrower, Aspentech, Inc. and Bank, as amended by
a certain letter agreement dated February 14, 2003, a certain First Loan
Modification Agreement dated June 27, 2003, a certain Second Loan Modification
Agreement dated September 10, 2004, a certain Third Loan Modification Agreement
dated January 28, 2005, a certain Fourth Loan Modification Agreement dated
April 1, 2005, a certain Fifth Loan Modification Agreement dated May 6, 2005, a
certain Sixth Loan Modification Agreement dated June 15, 2005, a certain Seventh
Loan Modification Agreement dated September, 2005, a certain Eighth Amendment to
Loan and Security Agreement dated November 22, 2005, a certain Ninth Loan
Modification Agreement dated July 17, 2006, a certain Tenth Loan Modification
Agreement dated September 15, 2006, and a certain Eleventh Loan Modification
Agreement dated September 27, 2006 (as amended, the "Loan Agreement").
Capitalized terms used but not otherwise defined herein shall have the same
meaning as in the Loan Agreement.

2.DESCRIPTION OF COLLATERAL.    Repayment of the Obligations is secured by the
Collateral as described in the Loan Agreement (together with any other
collateral security granted to Bank, the "Security Documents").

        Hereinafter, the Security Documents, together with all other documents
evidencing or securing the Obligations including the Export-Import Bank Loan and
Security Agreement dated as of January 30, 2003, as amended, shall be referred
to as the "Existing Loan Documents".

3.DESCRIPTION OF CHANGE IN TERMS.

Modifications to Loan Agreement.

(i)The Loan Agreement shall be amended by deleting the following text appearing
in Section 4 of the Schedule to the Loan Agreement:

"MATURITY DATE

(Section 6.1):    January 15, 2007"

and inserting in lieu thereof the folio ng:

"MATURITY DATE

(Section 6.1):    April 16, 2007"

--------------------------------------------------------------------------------

(ii)The Loan Agreement shall be amended by deleting Section 5(a) of the Schedule
thereto in its entirety and inserting in lieu thereof the following:

"a. Minimum Tangible Net Worth:

Borrower shall at all times maintain, to be tested monthly, as of the last day
of each month, a Tangible Net Worth of not less than the sum of (i) plus
(ii) below:

(i)

(a)from April 1, 2005 through and including April 30, 2005—$35,000,000;

(b)from May 1, 2005 through and including May 31, 2005—$25,000,000;

(c)from June 1, 2005 through and including June 30, 2005—$21,000,000;

(d)from July 1, 2005 through and including July 31, 2005—$14,000,000;

(e)from August 1, 2005 through and including August 31, 2005—$7,000,000;

(f)from September 1, 2005 through and including September 30, 2005—$21,000,000;

(g)from October 1, 2005 through and including October 31, 2005—$14,000,000;

(h)from November 1, 2005 through and including November 30, 2005—$7,000,000;

(i)from December 1, 2005 through and including December 31, 2005—$26,000,000;

(j)from January 1, 2006 through and including January 31, 2006—$19,000,000;

(k)from February 1, 2006 through and including February 28, 2006—$12,000,000;

(l)from March 1, 2006 through and including March 31, 2006—$31,000,000;

(m)from April 1, 2006 through and including April 30, 2006—$24,000,000;

(n)from May 1, 2006 through and including May 31, 2006—$17,000,000;

(o)from June 1, 2006 through and including June 30, 2006—$36,000,000;

(p)from July 1, 2006 through and including July 31, 2006—$29,000,000;

(q)from August 1, 2006 through and including August 31, 2006—$22,000,000;

(r)from September 1, 2006 through and including September 30, 2006—$41,000,000;

(s)from October 1, 2006 through and including October 31, 2006—$34,000,000;

(t)from November 1, 2006 through and including November 30, 2006—$27,000,000;

(u)from December 1, 2006 through and including December 31, 2006—$40,000,000;

(v)from January 1, 2007 through and including January 31, 2007—$32,000,000;

(w)from February 1, 2007 through and including February 28, 2007—$24,000,000;

(x)from March 1, 2007 through and including March 31, 2007—$40,000,000; and

(z)from April 1, 2007 and thereafter—$32,000,000.

(ii)75% of all consideration received after July 1, 2005 from proceeds from the
issuance of any equity securities of the Borrower (other than (i) the issuance
of stock options, restricted stock or other stock-based awards under the
Borrower's director or

2

--------------------------------------------------------------------------------

employee stock incentive plans, or (ii) stock purchases under the Borrower's
employee stock purchase plan)."

(iii)The Loan Agreement shall be amended by deleting Section 5(c) of the
Schedule thereto in its entirety and inserting in lieu thereof the following:

"c. Adjusted Quick Ratio:

Borrower shall maintain, at all times, to be tested monthly, an Adjusted Quick
Ratio of at least:

(a)from April 1, 2005 through and including April 30, 2005—1.35 to 1.0;

(b)from May 1, 2005 through and including May 31, 2005—1.20 to 1.0;

(c)from June 1, 2005 through and including June 30, 2005—1.15 to 1.0;

(d)from July 1, 2005 through and including July 31, 2005—1.05 to 1.0;

(e)from August 1, 2005 through and including August 31, 2005—0.95 to 1.0; (0
from September 1, 2005 through and including September 30, 2005—1.15 to 1.0;

(g)from October 1, 2005 through and including October 31, 2005—1.05 to 1.0;

(h)from November 1, 2005 through and including November 30, 2005—0.95 to 1.0;

(i)from December 1, 2005 through and including December 31, 2005—1.20 to 1.0

(j)from January 1, 2006 through and including January 31, 2006—1.10 to 1.0;

(k)from February 1, 2006 through and including February 28, 2006—1.00 to 1.0;
(1) from March 1, 2006 through and including March 31, 2006—1.25 to 1.0;

(m)from April 1, 2006 through and including April 30, 2006—1.15 to 1.0;

(n)from May 1, 2006 through and including May 31, 2006—1.05 to 1.0;

(o)from June 1, 2006 through December 31, 2006—1.25 to 1.0;

(p)from January 1, 2007 through and including February 28, 2007—1.15 to 1.0;

(q)from March 1, 2007 through and including March 31, 2007—1.25 to 1.0; and

(r)from April 1, 2007 through April 30, 2007—1.15 to 1.0."

4.FEES.    Borrower shall pay to Bank a modification fee of $6,300.00, which fee
shall be due on the date hereof and shall be deemed fully earned as of the date
hereof. Borrower shall also reimburse Bank for all legal fees and expenses
incurred in connection with this amendment to the Existing Loan Documents.

5.RATIFICATION OF NEGATIVE PLEDGE.    Borrower hereby ratifies, confirms and
reaffirms, all and singular, the terms and conditions of a certain Negative
Pledge Agreements each dated as of January 30, 2003 between Borrower and Bank,
and acknowledges, confirms and agrees that said Negative Pledge Agreement shall
remain in full force and effect.

6.RATIFICATION OF PERFECTION CERTIFICATES.    Borrower hereby ratifies, confirms
and reaffirms, all and singular, the terms and disclosures contained in certain
Perfection Certificates each dated as of January 30, 2003, as amended and
affected by Schedule 1 to the Fourth Amendment and Exhibit A to the Fourth
Amendment and acknowledges, confirms and agrees the disclosures and information
therein, in Schedule 3.10 to the Loan Agreement, in on Schedule 1 annexed to the
Tenth Loan Modification Agreement, and/or in connection with the formation of
subsidiaries as contemplated by the Guggenheim Transactions and the Key
Transactions (as defined

3

--------------------------------------------------------------------------------

in the Sixth Loan Modification Agreement and the Eleventh Loan Modification
Agreement, respectively), have not changed as of the date hereof.

7.CONSISTENT CHANGES.    The Existing Loan Documents are hereby amended wherever
necessary to reflect the changes described above.

8.RATIFICATION OF LOAN DOCUMENTS.    Borrower hereby ratifies, confirms, and
reaffirms all terms and conditions of all security: other collateral granted to
the Bank, and confirms that the indebtedness secured thereby includes, without
limitation, the Obligations.

9.NO DEFENSES OF BORROWER.    Borrower hereby acknowledges and agrees that
Borrower has no offsets, defenses, claims, or counterclaims against Bank with
respect to the Obligations, or otherwise, and that if Borrower now has, or ever
did have, any offsets, defenses, claims, or counterclaims against Bank, whether
known or unknown, at law or in equity, all of them are hereby expressly WAIVED
and Borrower hereby RELEASES Bank from any liability thereunder.

10.CONTINUING VALIDITY.    Borrower understands and agrees that in modifying the
existing Obligations, Bank is relying upon Borrower's representations,
warranties, and agreements, as set forth in the Existing Loan Documents. Except
as expressly modified pursuant to this Loan Modification Agreement, the terms of
the Existing Loan Documents remain unchanged and in full force and effect.
Bank's agreement to modifications to the existing Obligations pursuant to this
Loan Modification Agreement in no way shall obligate Bank to make any future
modifications to the Obligations. Nothing in this Loan Modification Agreement
shall constitute a satisfaction of the Obligations. It is the intention of Bank
and Borrower to retain as liable parties all makers of Existing Loan Documents,
unless the party is expressly released by Bank in writing.

11.COUNTERSIGNATURE.    This Loan Modification Agreement shall become effective
only when it shall have been executed by Borrower and Bank.

[Remainder of page intentionally left blank]

4

--------------------------------------------------------------------------------

        This Loan Modification Agreement is executed as a sealed instrument
under the laws of the Commonwealth of Massachusetts as of the date first written
above.

    BORROWER:
 
 
ASPEN TECHNOLOGY, INC.
 
 
By:
/s/ LEO S. VANNONI

--------------------------------------------------------------------------------

    Name: Leo S. Vannoni

--------------------------------------------------------------------------------

    Title: Treasurer

--------------------------------------------------------------------------------

 
 
BANK:
 
 
SILICON VALLEY BANK
 
 
By:
/s/ MICHAEL J. FELL

--------------------------------------------------------------------------------

    Name: Michael J. Fell

--------------------------------------------------------------------------------

    Title: Relationship Manager

--------------------------------------------------------------------------------

        The undersigned, ASPENTECH SECURITIES CORP., a Massachusetts
corporation, ratifies, confirms and reaffirms, all and singular, the terms and
conditions of a certain Unlimited Guaranty dated January 30, 2003 (the
"Guaranty") and a certain Security Agreement dated as of January 30, 2003 (the
"Security Agreement") and acknowledges, confirms and agrees that the Guaranty
and Security Agreement shall remain in full force and effect and shall in no way
be limited by the execution of this Loan Modification Agreement, or any other
documents, instruments and/or agreements executed and/or delivered in connection
herewith.

ASPENTECH SECURITIES CORP.    
By:
/s/ LEO S. VANNONI

--------------------------------------------------------------------------------

 
  Name: Leo S. Vannoni

--------------------------------------------------------------------------------

    Title: Treasurer

--------------------------------------------------------------------------------

   

5

--------------------------------------------------------------------------------

QuickLinks

TWELFTH LOAN MODIFICATION AGREEMENT