<PAGE>

                                                                  Exhibit 10.12


                      LOAN DOCUMENT MODIFICATION AGREEMENT
                        (NO. 3; DATED AS OF JUNE 1, 1999)

         LOAN DOCUMENT MODIFICATION AGREEMENT dated as of June 1, 1999 by and
among SILICON VALLEY BANK (the "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 Wellesley Office Park, 40 William
Street, Wellesley, Massachusetts 02181, doing business under the name "Silicon
Valley East," MOLDFLOW CORPORATION, a Delaware corporation ("MC"), MOLDFLOW
INTERNATIONAL PTY. LTD., a corporation organized under the laws of Australia and
a wholly-owned subsidiary of MC ("MIPL"), and MOLDFLOW PTY. LTD., a corporation
organized under the laws of Australia and a wholly-owned subsidiary of MIPL
("MPL"). MC, MIPL and MPL are sometimes each referred to herein as a "Borrower"
and collectively as the "Borrowers."

         1.       REFERENCE TO EXISTING LOAN DOCUMENTS.

         Reference is hereby made to that Loan Agreement dated April 23, 1998 by
and among the Bank and the Borrowers, as modified by a certain waiver letter
from the Bank dated September 17, 1998 and accepted by the Bank on September 18,
1998, as further amended by Loan Document Modification Agreement No. 2 dated as
of November 30, 1998 by and among the Bank and the Borrowers, and as further
amended by that certain letter amendment dated January 19, 1999 among the Bank
and the Borrowers (with the attached schedules and exhibits, the "CREDIT
AGREEMENT") and the Loan Documents referred to therein, including without
limitation that certain Amended and Restated Domestic Revolving Line Note of the
Borrowers dated November 30, 1998 in the principal amount of $2,650,000 (the
"Note"), that certain Amended and Restated Foreign Revolving Line Note of the
Borrowers dated November 30, 1998 in the principal amount of $600,000 and the
Security Documents referred to therein. Unless otherwise defined herein,
capitalized terms used in this Agreement shall have the same respective meanings
as set forth in the Credit Agreement.

         2.       EFFECTIVE DATE.

         This Agreement shall become effective as of June 1, 1999 (the
"EFFECTIVE DATE"), provided that the Bank shall have received two copies of this
Agreement, duly executed by the Borrowers, with the attached consents of
Moldflow (Europe) Ltd., Moldflow Vertriebs GmbH and Moldflow Japan K.K., duly
executed thereby, on or before August 27, 1999 and provided further, however, in
no event shall this Agreement become effective until signed by an officer of the
Bank in California.

<PAGE>
                                      -2-


         By the signature of its authorized officer below, each Borrower is
hereby representing that, except as modified in SCHEDULE A attached hereto, the
representations of the Borrowers set forth in the Loan Documents (including
those contained in the Credit Agreement, as amended by this Agreement) are true
and correct as of the Effective Date as if made on and as of such date.


<PAGE>


                                                        -2-

Finally, each Borrower (and each guarantor, signing below) agrees that, as of
the Effective Date, it has no defenses against its obligations to pay any
amounts under the Credit Agreement and the other Loan Documents.

         3.       DESCRIPTION OF CHANGE IN TERMS.

         As of the Effective Date, the Credit Agreement is modified in the
following respects:

                  1.       Section 6.7 is hereby amended and restated in its
entirety to read as follows:

                  "6.7     QUICK RATIO.  The Borrowers shall maintain as of the
         last day of each fiscal month, a ratio of Quick Assets to Current
         Liabilities as follows:  (a) at least 1.0 to 1.0 through June 30, 1999;
         and (b) 1.25 to 1.0 thereafter."

                  2.       Section 6.9 is hereby amended and restated in its
entirety to read as follows:

                  "6.9 PROFITABILITY. The Borrowers shall have (a) minimum Net
         Income of $100,000 for the quarter ending June 30, 1999; (b) minimum
         Net Income of $250,000 for the fiscal year ending June 30, 1999; and
         (c) minimum Net Income of $250,000 for the quarter ending September 30,
         1999."

                  3. Exhibit D to the Credit Agreement (Compliance Certificate)
is hereby amended in the form of Exhibit D attached hereto.

                  4. The Credit Agreement and the other Loan Documents are
hereby amended wherever necessary or appropriate to reflect the foregoing
changes.

         4.       CONTINUING VALIDITY.

<PAGE>
                                      -3-


         Upon the effectiveness hereof, (a) each reference in each Security
Instrument or other Loan Document to "the Credit Agreement," "thereunder,"
"thereof," "therein" or words of like import referring to the Credit Agreement,
shall mean and be a reference to the Credit Agreement, as amended hereby, each
reference in the Credit Agreement and each other Loan Document to the Domestic
Revolving Line Note and the Foreign Revolving Line Note shall mean and be a
reference to the Amended Domestic Revolving Note and the Amended Foreign
Revolving Note, respectively. Except as specifically set forth above, the Credit
Agreement and each of the Notes shall remain in full force and effect and is
hereby ratified and confirmed. Each of the other Loan Documents is in full force
and effect and is hereby ratified and confirmed. The amendments and waiver set
forth above (i) do not constitute a waiver or modification of any term,
condition or covenant of the Credit Agreement or any other Loan Document, other
than as expressly set forth herein, and (ii) shall not prejudice any rights
which the Bank may now or hereafter have under or in connection with the Credit
Agreement, as modified hereby, or the other Loan Documents and shall not
obligate the Bank to assent to any further modifications.

         5.       MISCELLANEOUS.

                  1. This Agreement may be signed in one or more counterparts
each of which taken together shall constitute one and the same document.

                  2. THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE COMMONWEALTH OF MASSACHUSETTS WITHOUT REGARD TO
PRINCIPLES RELATING TO CONFLICTS OF LAW OR CHOICE OF LAW.

                  3. THE BORROWER ACCEPTS FOR ITSELF AND IN CONNECTION WITH ITS
PROPERTIES, UNCONDITIONALLY, THE NON-EXCLUSIVE JURISDICTION OF ANY STATE OR
FEDERAL COURT OF COMPETENT JURISDICTION IN THE COMMONWEALTH OF MASSACHUSETTS IN
ANY ACTION, SUIT, OR PROCEEDING OF ANY KIND AGAINST IT WHICH ARISES OUT OF OR BY
REASON OF THIS LOAN MODIFICATION AGREEMENT; PROVIDED, HOWEVER, THAT IF FOR ANY
REASON LENDER CANNOT AVAIL ITSELF OF THE COURTS OF THE COMMONWEALTH OF
MASSACHUSETTS, THEN VENUE SHALL LIE IN SANTA CLARA COUNTY, CALIFORNIA.

                  4. The Borrower agrees to promptly pay on demand all costs and
expenses of the Bank in connection with the preparation, reproduction, execution
and delivery of this letter amendment and the other instruments and documents to
be delivered hereunder, including the reasonable fees and out-of-pocket expenses
of Sullivan & Worcester, special counsel for the Bank with respect thereto.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]


<PAGE>
                                      -4-


         IN WITNESS WHEREOF, the Bank and the Borrower have caused this
Agreement to be signed under seal by their respective duly authorized officers
as of the date set forth above.

                                            SILICON VALLEY EAST, a Division
                                              of Silicon Valley Bank

                                            By: /s/ Andrew H. Tsao
                                                ---------------------------
                                                Andrew H. Tsao
                                                Senior Vice President


                                            SILICON VALLEY BANK

                                            By: /s/ illegible
                                                ---------------------------
                                                Name:
                                                Title:
                                                (signed in Santa Clara, CA)


                                            MOLDFLOW CORPORATION

                                            By: /s/ Marc Dulude
                                                ---------------------------
                                                Name:  Marc Dulude
                                                Title: President, CEO


MOLDFLOW INTERNATIONAL PTY.                 MOLDFLOW INTERNATIONAL PTY.
    LTD.                                        LTD.

By: /s/ Marc Dulude                         By: /s/ Suzanne Rogers
    ---------------------------                 ---------------------------
    Name:  Marc Dulude                          Name:  Suzanne Rogers
    Title: Director                             Title: Director


MOLDFLOW PTY. LTD.                          MOLDFLOW PTY. LTD.

By: /s/ Marc Dulude                         By: /s/ Suzanne Rogers
    ---------------------------                 ---------------------------
    Name:  Marc Dulude                          Name:  Suzanne Rogers
    Title: Director                             Title: Director

<PAGE>



                                                                      SCHEDULE A

            MODIFICATION OF OR SUPPLEMENTS TO THE DISCLOSURE SCHEDULE

                                      None


<PAGE>


                                     CONSENT

         The undersigned, as Guarantor under a certain Guarantee dated as of May
21, 1998 (the "Guarantee") in favor of Silicon Valley Bank, hereby consents to
the foregoing Loan Document Modification Agreement (the "Amendment") and hereby
confirms and agrees that the Guarantee is, and shall continue to be, in full
force and effect and is hereby ratified and confirmed in all respects, except
that, upon the effectiveness of, and on and after the date of, said Amendment,
each reference in the Guarantee and in each other Loan Document (as defined in
the Credit Agreement) to which the undersigned is a party, including, to "the
Credit Agreement", the "Loan Agreement," "thereunder," "thereof," "therein" or
words of like import referring to the Credit Agreement, shall mean and be a
reference to the Credit Agreement, as amended hereby, and each reference in the
Guarantee and in each such other Loan Document to "the Notes," "thereof,"
"therein," "thereunder" or words of like import referring to the Notes shall
mean and be a reference to the Amended Domestic Revolving Note and the Amended
Foreign Revolving Note.

                                                  MOLDFLOW (EUROPE) LTD.

                                                  By:___________________________
                                                      Name:
                                                      Title:


<PAGE>


                                     CONSENT

         The undersigned, as Guarantor under a certain Guarantee dated as of May
21, 1998 (the "Guarantee") in favor of Silicon Valley Bank, hereby consents to
the foregoing Loan Document Modification Agreement (the "Amendment") and hereby
confirms and agrees that the Guarantee is, and shall continue to be, in full
force and effect and is hereby ratified and confirmed in all respects, except
that, upon the effectiveness of, and on and after the date of, said Amendment,
each reference in the Guarantee and in each other Loan Document (as defined in
the Credit Agreement) to which the undersigned is a party, including, to "the
Credit Agreement," the "Loan Agreement," "thereunder," "thereof," "therein" or
words of like import referring to the Credit Agreement, shall mean and be a
reference to the Credit Agreement, as amended hereby, and each reference in the
Guarantee and in each such other Loan Document to "the Notes," "thereof,"
"therein," "thereunder" or words of like import referring to the Notes shall
mean and be a reference to the Amended Domestic Revolving Note and the Amended
Foreign Revolving Note.

                                                 MOLDFLOW VERTRIEBS GmbH

                                                 By:___________________________
                                                     Name:
                                                     Title:


<PAGE>


                                     CONSENT

         The undersigned, as Guarantor under a certain Guarantee dated as of
June 11, 1998 (the "Guarantee") in favor of Silicon Valley Bank, hereby consents
to the foregoing Loan Document Modification Agreement (the "Amendment") and
hereby confirms and agrees that the Guarantee is, and shall continue to be, in
full force and effect and is hereby ratified and confirmed in all respects,
except that, upon the effectiveness of, and on and after the date of, said
Amendment, each reference in the Guarantee and in each other Loan Document (as
defined in the Credit Agreement) to which the undersigned is a party, including,
to "the Credit Agreement," the "Loan Agreement," "thereunder," "thereof,"
"therein" or words of like import referring to the Credit Agreement, shall mean
and be a reference to the Credit Agreement, as amended hereby, and each
reference in the Guarantee and in each such other Loan Document to "the Notes,"
"thereof," "therein," "thereunder" or words of like import referring to the
Notes shall mean and be a reference to the Amended Domestic Revolving Note and
the Amended Foreign Revolving Note.

                                                 MOLDFLOW JAPAN K.K.

                                                 By:___________________________
                                                     Name:
                                                     Title:


<PAGE>

                                    EXHIBIT D
                             COMPLIANCE CERTIFICATE


TO:        SILICON VALLEY BANK

FROM:      MOLDFLOW CORPORATION

         The undersigned authorized officer of Moldflow Corporation hereby
certifies that in accordance with the terms and conditions of the Loan Agreement
among Moldflow Corporation, Moldflow International Pty. Ltd. and Moldflow Pty.
Ltd., and the Bank (the "Agreement"), (i) Borrower is in complete compliance for
the period ending _______with all required covenants except as noted below and
(ii) all representations and warranties of Borrower stated in the Agreement are
true and correct in all material respects as of the date hereof. Attached
herewith are the required documents supporting the above certification. The
Officer further certifies that these are prepared in accordance with Generally
Accepted Accounting Principles (GAAP) and are consistently applied from one
period to the next except as explained in an accompanying letter or footnotes.
The Officer expressly acknowledges that no borrowings may be requested by the
Borrower at any time or date of determination that Borrower is not in compliance
with any of the terms of the Agreement, and that such compliance is determined
not just at the date this certificate is delivered.

           PLEASE INDICATE COMPLIANCE STATUS BY CIRCLING YES/NO UNDER
                               "COMPLIES" COLUMN.

<TABLE>
<CAPTION>

REPORTING COVENANT                    REQUIRED                                             COMPLIES

<S>                                   <C>                                           <C>              <C>
*Monthly financial statements         Monthly within 25 days                        Yes              No
Annual (CPA Audited)                  FYE within 120 days                           Yes              No
10Q and 10K                           Within 5 days after filing with the SEC       Yes              No
*A/R Agings                           Monthly within 25 days                        Yes              No
A/R Audit                             Initial and Semi-Annual                       Yes              No

* when borrowing

<CAPTION>

FINANCIAL COVENANT                    REQUIRED                                      ACTUAL           COMPLIES

<S>                                   <C>                                        <C>                 <C>
Maintain on a Monthly Basis:
  Minimum Quick Ratio                 0.8:1.0 through 2/28/99;
                                      1.0:1.0 from 3/31/99 through
                                      6/30/99, 1.25:1.0 thereafter               ____:1.0            Yes      No

Maintain on a Quarterly Basis:
  Minimum Tangible Net Worth          $500,000 at 9/30/98                        $_______            Yes      No

Profitability:  Quarterly             $100,000 for quarter ended 6/30/99
                                      $250,000 for quarter ended 9/30/99         $_______            Yes      No

Annually                              $250,000 for FYE 6/30/99                   $_______            Yes      No

</TABLE>

COMMENTS REGARDING EXCEPTIONS:  See Attached.


Sincerely,

MOLDFLOW CORPORATION

By:__________________________________
     Name:
     Title:
     Date: