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                                                                     Exhibit 4.2

                                    AMENDMENT
                                       TO
                                RIGHTS AGREEMENT

              THIS AMENDMENT TO RIGHTS AGREEMENT (this "Amendment"), dated as of
January 8, 2003, is between Mercator Software, Inc., a Delaware corporation (the
"Company"), and THE BANK OF NEW YORK, a New York banking corporation, as rights
agent (the "Rights Agent") under the Rights Agreement, dated as of September 2,
1998, between the Company (then known as "TSI International Software Ltd.") and
the Rights Agent (the "Rights Agreement").

              The Company and Rights Agent agree that the Rights Agreement shall
be amended as follows:

              1.   Section 7(b) of the Rights Agreement shall be amended to read
as follows:

              "(b) The purchase price for each one one-hundredth of a Preferred
Share pursuant to the exercise of a Right (the "Purchase Price") shall be
$20.00, shall be subject to adjustment from time to time as provided in Sections
11 and 13 hereof and shall be payable in lawful money of the United States of
America in accordance with paragraph (c) below."

              2.   Any adjustment to the Purchase Price pursuant to Section 11
(a) or Section 11(b) through 11(o) of the Rights Agreement shall be based solely
on events occurring after the date of this Amendment.

              3.   Section 24(a) of the Rights Agreement shall be amended to
delete the second sentence, so that Section 24(a) in its entirety reads as
follows:

              "(a) The Board of Directors of the Company may, at its option, at
any time after any Person becomes an Acquiring Person, authorize and direct the
exchange of all or part of the then outstanding and exercisable Rights (which
shall not include Rights that have become void pursuant to the provisions of
Section 11(a)(ii) hereof) for Common Shares at an exchange ratio (the "Exchange
Ratio") of one Common Share per Rights, appropriately adjusted to reflect any
stock split, stock dividend or similar transaction occurring after the date
hereof."

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              4.   Conforming changes shall be made to the Form of Right
Certificate attached as Exhibit B to the Rights Agreement and to the Summary of
Rights to Purchase Preferred Shares attached as Exhibit C to the Rights
Agreement.

              5.   This Amendment shall be binding upon and shall inure to the
benefit of each of the parties and their respective successors and assigns.

              6.   Except as expressly provided in this Amendment, all
provisions of the Rights Agreement shall remain in full force and effect and
shall be unchanged by this Amendment.

              7.   Unless otherwise defined herein, all defined terms used
herein shall have the meanings given to them in the Rights Agreement.

              8.   This Amendment shall be governed by, and interpreted in
accordance with, the laws of the State of Delaware applicable to contracts to be
made and performed entirely within that State.

              IN WITNESS WHEREOF, the parties have caused this Amendment to be
duly executed as of the day and year first

above written.

                                           MERCATOR SOFTWARE, INC.

                                           By /s/ Gerald E. Klein
                                              ----------------------------------
                                                 Name: Gerald E. Klein
                                                 Title: Assistant Secretary

                                           THE BANK OF NEW YORK, RIGHTS AGENT

                                           By /s/ Alexander Pabon
                                              ----------------------------------
                                                 Name: Alexander Pabon
                                                 Title: Assistant Vice-President

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