<PAGE>

As filed with the Securities and Exchange Commission on November 15, 2001

                                                   Registration No. 333- _______


================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, DC. 20549

                                   FORM S-8

                         REGISTRATION STATEMENT UNDER
                          THE SECURITIES ACT OF 1933

                            MERCATOR SOFTWARE, INC.
            (Exact name of registrant as specified in its charter)

           Delaware                                          06-1132156
(State or other jurisdiction of                           (I.R.S. Employer
incorporation or organization)                           Identification No.)

                                45 Danbury Road
                           Wilton, Connecticut 06897
                                (203) 761-8600
              (Address of Principal Executive Offices) (Zip Code)
                         _____________________________

                          1997 Equity Incentive Plan
                           (Full title of the plan)
                         _____________________________

                                  Roy C. King
                President, Chief Executive Officer and Chairman
                            Mercator Software, Inc.
                                45 Danbury Road
                           Wilton, Connecticut 06897
                                (203) 761-8600
          (Name and address including zip code and telephone number,
                  including area code, of agent for service)

                         _____________________________

                                  Copies to:

                            Heather S. Stone, Esq.
                        TESTA, HURWITZ & THIBEAULT, LLP
                                125 High Street
                          Boston, Massachusetts 02110
                                (617) 248-7000

================================================================================

                        CALCULATION OF REGISTRATION FEE
<TABLE>
<CAPTION>
=========================================================================================================

                                                 Proposed maximum    Proposed maximum
   Title of securities        Amount to be           offering           aggregate           Amount of
    to be registered         registered/(1)/     price per share      offering price     registration fee
    ----------------         ---------------     ---------------      --------------     ----------------
<S>                        <C>                  <C>                 <C>                 <C>
1997 Equity Incentive
 Plan

Common Stock, par value           2,900,348(2)               $5.28      $15,313,837.44        $3,828.46
 $.01 per share                      31,000(3)               $4.36      $   135,160.00        $   33.79
                                     22,000(3)               $3.50      $    77,000.00        $   19.25
                                      6,250(3)               $2.66      $    16,625.00        $    4.16
                                      7,500(3)               $2.84      $    21,300.00        $    5.33
                                     10,000(3)               $2.55      $    25,500.00        $    6.38
                                      7,500(3)               $2.71      $    20,325.00        $    5.08
                                     15,402(3)               $2.29      $    35,270.58        $    8.82
TOTAL                             3,000,000                                                   $3,911.27

=========================================================================================================
</TABLE>


/(1)/ Upon the filing and effectiveness of this Registration Statement on Form
      S-8, the total number of shares of Common Stock registered pursuant to the
      1997 Equity Incentive Plan will be 10,167,828, plus such additional shares
      as may be required pursuant to the plan in the event of a stock dividend,
      split-up of shares, recapitalization or other similar change in the Common
      Stock.

/(2)/ Pursuant to Rule 457(c) and (h)(1) of Regulation C of the Securities Act,
      the price of $5.28 per share, is the average of the high and low prices of
      the Common Stock as reported on The Nasdaq National Market on November 13,
      2001, and is set forth solely for purposes of calculating the filing fee
      for those shares without a fixed exercise price.

/(3)/ Such shares are issuable upon the exercise of outstanding options with
      fixed exercise prices. Pursuant to Rule 457(h), the aggregate offering
      price and the fee have been computed upon the basis of the price at which
      the options may be exercised. The offering price per share set forth for
      such shares is the exercise price per share at which such options are
      exercisable.
<PAGE>

         This Registration Statement registers additional securities of the same
class as other securities for which (i) Registration Statement No. 333-30631 on
Form S-8 as filed with the Securities and Exchange Commission (the "Commission")
on July 2, 1997, relating to the Registrant's (as defined herein) 1997 Employee
Stock Purchase Plan, is effective; (ii) Registration Statement No. 333-37969 on
Form S-8 as filed with the Commission on October 15, 1997, relating to the
Registrant's 1997 Equity Incentive Plan and 1997 Director's Stock Option Plan,
is effective; (iii) Registration Statement No. 333-89951 on Form S-8 as filed
with the Commission on October 29, 1999, relating to Novera Software, Inc.'s
1996 Stock Option Plan, is effective; (iv) Registration Statement No. 333-32002
on Form S-8 as filed with the Commission on March 8, 2000, relating to the
Registrant's 1997 Equity Incentive Plan, is effective; and (v) Registration
Statement No. 333-59240 on Form S-8 as filed with the Commission on April 19,
2001, relating to the Registrant's 1997 Equity Incentive Plan, is effective.
Pursuant to General Instruction E to Form S-8, the contents of the above-listed
Registration Statements are hereby incorporated by reference.

                                    PART II

              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference.
         ---------------------------------------

         The following documents filed by Mercator Software, Inc. (the
"Registrant") with the Commission pursuant to the Securities Exchange Act of
1934, as amended (the "Exchange Act"), are incorporated in this Registration
Statement by reference as of their respective dates:

         (a)  The Registrant's Annual Report on Form 10-K for the fiscal year
              ended December 31, 2000, filed with the Commission on March 30,
              2001;

         (b)  The Registrant's Quarterly Report on Form 10-Q for the fiscal
              quarter ended March 31, 2001 (filed with the Commission on May 15,
              2001), the Registrant's Quarterly Report on Form 10-Q for the
              fiscal quarter ended June 30, 2001 (filed with the Commission on
              August 14, 2001), the Registrant's Current Report on Form 8-K
              (filed with the Commission on October 1, 2001) and the
              Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
              ended September 30, 2001 (filed with the Commission on November
              14, 2001); and

         (c)  The section entitled "Description of Registrant's Securities to be
              Registered" contained in the Registrant's registration statement
              on Form 8-A filed with the Commission on June 6, 1997 pursuant to
              Section 12(g) of the Exchange Act and incorporating by reference
              the information contained in the Registrant's Registration
              Statement on Form S-1 (SEC File No. 333-27293) initially filed
              with the Commission on March 6, 1997 as amended.

         All documents subsequently filed with the Commission by the Registrant
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act, prior to
the filing of a post-effective amendment which indicates that all securities
offered herein have been sold or which deregisters all securities then remaining
unsold, shall be deemed to be incorporated by reference in this Registration
Statement and to be a part hereof from the date of filing of such documents.
<PAGE>

Item 8.  Exhibits.
         --------

                Exhibit No.                    Description of Exhibit
                -----------                    ----------------------

                        4.1           Amended and Restated Certificate of
                                      Incorporation, as amended, of the
                                      Registrant (filed as Exhibit 3.1 to the
                                      Registrant's Quarterly Report on Form 10-Q
                                      on November 14, 2000, File No. 000-22667
                                      (7674707), and incorporated by reference
                                      herein).*

                        4.2           Amended and Restated By-Laws of the
                                      Registrant (filed as Exhibit 3.1 to the
                                      Registrant's Registration Statement on
                                      Form 8-A on September 4, 1998, File No.
                                      000-22667 (98704715), and incorporated by
                                      reference herein).*

                        4.3           1997 Equity Incentive Plan, as amended, of
                                      the Registrant (filed as Exhibit 10.1 to
                                      the Registrant's Quarterly Report on Form
                                      10-Q on November 14, 2001, File No. 000-
                                      22667 and incorporated be reference
                                      herein).*

                        4.4           Certificate of Designation specifying the
                                      terms of the Series A Junior Participating
                                      Preferred Stock of the Registrant (filed
                                      as Exhibit 3.2 to the Registrant's
                                      Registration Statement on Form 8-A on
                                      September 4, 1998, File No. 000-22667
                                      (98704715), and incorporated by reference
                                      herein).*

                        4.5           Rights Agreement dated September 2, 1998
                                      between the Registrant and the Bank of New
                                      York (filed as Exhibit 3.3 to the
                                      Registrant's Registration Statement on
                                      Form 8-A on September 4, 1998, File No.
                                      000-22667 (98704715), and incorporated by
                                      reference herein).*

                        5.1           Opinion of Testa, Hurwitz & Thibeault,
                                      LLP.**

                       23.1           Consent of Testa, Hurwitz & Thibeault, LLP
                                      (contained in its opinion as Exhibit 5.1).

                       23.2           Consent of KPMG, LLP.**

                       24.1           Power of Attorney (included as part of the
                                      signature page of this Registration
                                      Statement).

          *Not-filed herewith. In accordance with Rule 411 promulgated pursuant
to the Securities Act of 1933, as amended, reference is made to the documents
previously filed with the commission, which are incorporated by reference
herein.
          **Filed herewith.

     Item 9. Undertakings.
             -------------

            (a)  The undersigned Registrant hereby undertakes:

                 (1)   To file, during any period in which offers or sales are
                       being made, a post-effective amendment to this
                       Registration Statement:
<PAGE>

                    (i)   To include any prospectus required by Section 10(a)(3)
                          of the Securities Act of 1933;

                    (ii)  To reflect in the prospectus any facts or events
                          arising after the effective date of the Registration
                          Statement (or the most recent post-effective amendment
                          thereof) which, individually or in the aggregate,
                          represent a fundamental change in the information set
                          forth in the Registration Statement; and

                    (iii) To include any material information with respect to
                          the plan of distribution not previously disclosed in
                          the Registration Statement or any material change to
                          such information in the Registration Statement;

                    provided however, that paragraphs (a) (1) (i) and (a) (1)
                    (ii) do not apply if the registration statement is on Form
                    S-3, Form S-8 or Form F-3, and the information required to
                    be included in a post-effective amendment by those
                    paragraphs is contained in periodic reports filed with or
                    furnished to the Commission by the registrant pursuant to
                    Section 13 or 15 (d) of the Securities Exchange Act of 1934
                    that are incorporated by reference in the registration
                    statement.


          (2)       That, for the purpose of determining any liability under the
                    Securities Act of 1933, each such post-effective amendment
                    shall be deemed to be a new registration statement relating
                    to the securities offered therein, and the offering of such
                    securities at that time shall be deemed to be the initial
                    bona fide offering thereof.

          (3)       To remove from registration by means of a post-effective
                    amendment any of the securities being registered which
                    remain unsold at the termination of the offering.

     (b)  The undersigned Registrant hereby undertakes that, for purposes of
          determining any liability under the Securities Act of 1933, each
          filing of the Registrant's annual report pursuant to Section 13(a) or
          Section 15(d) of the Securities Exchange Act of 1934 (and, where
          applicable, each filing of any employee benefit plan's annual report
          pursuant to Section 15(d) of the Securities Exchange Act of 1934) that
          is incorporated by reference in the Registration Statement shall be
          deemed to be a new registration statement relating to the securities
          offered therein, and the offering of such securities at that time
          shall be deemed to be the initial bona fide offering thereof.

     (c)  Insofar as indemnification for liabilities arising under the
          Securities Act of 1933 may be permitted to directors, officers and
          controlling persons of the Registrant pursuant to the foregoing
          provisions, or otherwise, the Registrant has been advised that in the
          opinion of the Securities and Exchange Commission such indemnification
          is against public policy as expressed in the Act and is, therefore,
          unenforceable.  In the event that a claim for indemnification against
          such liabilities (other than the payment by the Registrant of expenses
          incurred or paid by a director, officer or controlling person of the
          Registrant in the successful defense of any action, suit or
          proceeding) is asserted by such director, officer or controlling
          person in connection with the securities being registered, the
          Registrant will, unless in the opinion of its counsel the matter has
          been settled by controlling precedent, submit to a court of
          appropriate jurisdiction the question whether such indemnification by
          it is against public policy as expressed in the Act and will be
          governed by the final adjudication of such issue.
<PAGE>

                                  SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Wilton, the State of Connecticut, on this 15/th/ day
of November 2001.

                             MERCATOR SOFTWARE, INC.


                             By: /s/ Roy C. King
                                 -----------------------------------------------
                                 Roy C. King
                                 President, Chief Executive Officer and Chairman

                               POWER OF ATTORNEY

     EACH SUCH PERSON WHOSE SIGNATURE appears below constitutes and appoints,
jointly and severally, Roy C. King and Kenneth Hall and each of them, with full
power to act without the other, his true and lawful attorney-in-fact and agent,
with the power of substitution and resubstitution, for him and in his name,
place and stead, in any and all capacities, to sign any amendments to this
Registration Statement on Form S-8 (including post-effective amendments) and to
file the same, with all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, hereby ratifying and
confirming all that said attorney-in-fact, or his or her substitute or
substitutes, may do or cause to be done by virtue hereof.

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the date indicated.

<TABLE>
<CAPTION>
             Signature                                Title                                   Date
             ---------                                -----                                   ----
<S>                                   <C>                                               <C>
/s/ Roy C. King                       President, Chief Executive Officer                November 15, 2001
------------------------------------  and Chairman of the Board of Directors
  Roy C. King

/s/ Kenneth Hall                      Sr. Vice President, Chief Financial               November 15, 2001
------------------------------------  Officer and Treasurer
  Kenneth Hall

/s/ James P. Schadt                   Vice-Chairman of the Board of                     November 15, 2001
------------------------------------  Directors
  James P. Schadt

/s/ Diane P. Baker                    Director                                          November 15, 2001
------------------------------------
  Diane P. Baker

/s/ Constance F. Galley               Director                                          November 15, 2001
------------------------------------
  Constance F. Galley

/s/ Ernest E. Keet                    Director                                          November 15, 2001
------------------------------------
  Ernest E. Keet

/s/ Richard Little                    Director                                          November 15, 2001
------------------------------------
  Richard Little

/s/ Dennis G. Sisco                   Director                                          November 15, 2001
------------------------------------
  Dennis G. Sisco

/s/ Mark C. Stevens                   Director                                          November 15, 2001
------------------------------------
  Mark C. Stevens
</TABLE>
<PAGE>

                               INDEX TO EXHIBITS

     Exhibit                            Description of Exhibit
     -------                            ----------------------

        4.1              Amended and Restated Certificate of Incorporation, as
                         amended, of the Registrant (filed as Exhibit 3.1 to the
                         Registrant's Quarterly Report on Form 10-Q on November
                         14, 2000, File No. 000-22667 (7674707) and incorporated
                         by reference herein).*

        4.2              Amended and Restated By-Laws of the Registrant (filed
                         as Exhibit 3.1 to the Registrant's Registration
                         Statement on Form 8-A on September 4, 1998, File No.
                         000-22667 (98704715), and incorporated by reference
                         herein).*

        4.3              1997 Equity Incentive Plan, as amended, of the
                         Registrant (filed as Exhibit 10.1 to the
                         Registrant's Quarterly Report on Form 10-Q on November
                         14, 2001, File No. 000-22667 and incorporated be
                         reference herein).*

        4.4              Certificate of Designation specifying the terms of the
                         Series A Junior Participating Preferred Stock of the
                         Registrant (filed as Exhibit 3.2 to the Registrant's
                         Registration Statement on Form 8-A on September 4,
                         1998, File No. 000-22667 (98704715), and incorporated
                         by reference herein).*

        4.5              Rights Agreement dated September 2, 1998 between the
                         Registrant and the Bank of New York (filed as Exhibit
                         3.3 to the Registrant's Registration Statement on Form
                         8-A on September 4, 1998, File No. 000-22667
                         (98704715), and incorporated by reference herein).*

        5.1              Opinion of Testa, Hurwitz & Thibeault, LLP.**

       23.1              Consent of Testa, Hurwitz & Thibeault, LLP (contained
                         in its opinion as Exhibit 5.1).

       23.2              Consent of KPMG, LLP.**

       24.1              Power of Attorney (included as part of the signature
                         page of this Registration Statement).


   *Not-filed herewith. In accordance with Rule 411 promulgated pursuant to the
Securities Act of 1933, as amended, reference is made to the documents
previously filed with the commission, which are incorporated by reference
herein.
   **Filed herewith.
[{"type": "S-8", "sequence": "1", "filename": "ds8.txt", "description": "FORM S-8", "secsgml_size_bytes": 23130}]
{"company-data": {"conformed-name": "MERCATOR SOFTWARE INC", "cik": "0001039276", "assigned-sic": "7372", "irs-number": "061132156", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-73432", "film-number": "1793020"}, "business-address": {"street1": "45 DANBURY RD", "city": "WILTON", "state": "CT", "zip": "06897", "phone": "2037617600"}, "mail-address": {"street1": "45 DANBURY", "city": "WILTON", "state": "CT", "zip": "06897"}, "former-company": {"former-conformed-name": "TSI INTERNATIONAL SOFTWARE LTD", "date-changed": "19970514"}}
As filed with the Securities and Exchange Commission on November 15, 2001

                                                   Registration No. 333- _______

================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, DC. 20549

                                   FORM S-8

                         REGISTRATION STATEMENT UNDER
                          THE SECURITIES ACT OF 1933

                            MERCATOR SOFTWARE, INC.
            (Exact name of registrant as specified in its charter)

           Delaware                                          06-1132156
(State or other jurisdiction of                           (I.R.S. Employer
incorporation or organization)                           Identification No.)

                                45 Danbury Road
                           Wilton, Connecticut 06897
                                (203) 761-8600
              (Address of Principal Executive Offices) (Zip Code)
                         _____________________________

                          1997 Equity Incentive Plan
                           (Full title of the plan)
                         _____________________________

                                  Roy C. King
                President, Chief Executive Officer and Chairman
                            Mercator Software, Inc.
                                45 Danbury Road
                           Wilton, Connecticut 06897
                                (203) 761-8600
          (Name and address including zip code and telephone number,
                  including area code, of agent for service)

                         _____________________________

                                  Copies to:

                            Heather S. Stone, Esq.
                        TESTA, HURWITZ & THIBEAULT, LLP
                                125 High Street
                          Boston, Massachusetts 02110
                                (617) 248-7000

================================================================================

                        CALCULATION OF REGISTRATION FEE
=========================================================================================================

                                                 Proposed maximum    Proposed maximum
   Title of securities        Amount to be           offering           aggregate           Amount of
    to be registered         registered/(1)/     price per share      offering price     registration fee
    ----------------         ---------------     ---------------      --------------     ----------------
1997 Equity Incentive
 Plan

Common Stock, par value           2,900,348(2)               $5.28      $15,313,837.44        $3,828.46
 $.01 per share                      31,000(3)               $4.36      $   135,160.00        $   33.79
                                     22,000(3)               $3.50      $    77,000.00        $   19.25
                                      6,250(3)               $2.66      $    16,625.00        $    4.16
                                      7,500(3)               $2.84      $    21,300.00        $    5.33
                                     10,000(3)               $2.55      $    25,500.00        $    6.38
                                      7,500(3)               $2.71      $    20,325.00        $    5.08
                                     15,402(3)               $2.29      $    35,270.58        $    8.82
TOTAL                             3,000,000                                                   $3,911.27

=========================================================================================================
/(1)/ Upon the filing and effectiveness of this Registration Statement on Form
      S-8, the total number of shares of Common Stock registered pursuant to the
      1997 Equity Incentive Plan will be 10,167,828, plus such additional shares
      as may be required pursuant to the plan in the event of a stock dividend,
      split-up of shares, recapitalization or other similar change in the Common
      Stock.

/(2)/ Pursuant to Rule 457(c) and (h)(1) of Regulation C of the Securities Act,
      the price of $5.28 per share, is the average of the high and low prices of
      the Common Stock as reported on The Nasdaq National Market on November 13,
      2001, and is set forth solely for purposes of calculating the filing fee
      for those shares without a fixed exercise price.

/(3)/ Such shares are issuable upon the exercise of outstanding options with
      fixed exercise prices. Pursuant to Rule 457(h), the aggregate offering
      price and the fee have been computed upon the basis of the price at which
      the options may be exercised. The offering price per share set forth for
      such shares is the exercise price per share at which such options are
      exercisable.
This Registration Statement registers additional securities of the same
class as other securities for which (i) Registration Statement No. 333-30631 on
Form S-8 as filed with the Securities and Exchange Commission (the "Commission")
on July 2, 1997, relating to the Registrant's (as defined herein) 1997 Employee
Stock Purchase Plan, is effective; (ii) Registration Statement No. 333-37969 on
Form S-8 as filed with the Commission on October 15, 1997, relating to the
Registrant's 1997 Equity Incentive Plan and 1997 Director's Stock Option Plan,
is effective; (iii) Registration Statement No. 333-89951 on Form S-8 as filed
with the Commission on October 29, 1999, relating to Novera Software, Inc.'s
1996 Stock Option Plan, is effective; (iv) Registration Statement No. 333-32002
on Form S-8 as filed with the Commission on March 8, 2000, relating to the
Registrant's 1997 Equity Incentive Plan, is effective; and (v) Registration
Statement No. 333-59240 on Form S-8 as filed with the Commission on April 19,
2001, relating to the Registrant's 1997 Equity Incentive Plan, is effective.
Pursuant to General Instruction E to Form S-8, the contents of the above-listed
Registration Statements are hereby incorporated by reference.

                                    PART II

              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference.
         ---------------------------------------

         The following documents filed by Mercator Software, Inc. (the
"Registrant") with the Commission pursuant to the Securities Exchange Act of
1934, as amended (the "Exchange Act"), are incorporated in this Registration
Statement by reference as of their respective dates:

         (a)  The Registrant's Annual Report on Form 10-K for the fiscal year
              ended December 31, 2000, filed with the Commission on March 30,
              2001;

         (b)  The Registrant's Quarterly Report on Form 10-Q for the fiscal
              quarter ended March 31, 2001 (filed with the Commission on May 15,
              2001), the Registrant's Quarterly Report on Form 10-Q for the
              fiscal quarter ended June 30, 2001 (filed with the Commission on
              August 14, 2001), the Registrant's Current Report on Form 8-K
              (filed with the Commission on October 1, 2001) and the
              Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
              ended September 30, 2001 (filed with the Commission on November
              14, 2001); and

         (c)  The section entitled "Description of Registrant's Securities to be
              Registered" contained in the Registrant's registration statement
              on Form 8-A filed with the Commission on June 6, 1997 pursuant to
              Section 12(g) of the Exchange Act and incorporating by reference
              the information contained in the Registrant's Registration
              Statement on Form S-1 (SEC File No. 333-27293) initially filed
              with the Commission on March 6, 1997 as amended.

         All documents subsequently filed with the Commission by the Registrant
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act, prior to
the filing of a post-effective amendment which indicates that all securities
offered herein have been sold or which deregisters all securities then remaining
unsold, shall be deemed to be incorporated by reference in this Registration
Statement and to be a part hereof from the date of filing of such documents.
Item 8.  Exhibits.
         --------

                Exhibit No.                    Description of Exhibit
                -----------                    ----------------------

                        4.1           Amended and Restated Certificate of
                                      Incorporation, as amended, of the
                                      Registrant (filed as Exhibit 3.1 to the
                                      Registrant's Quarterly Report on Form 10-Q
                                      on November 14, 2000, File No. 000-22667
                                      (7674707), and incorporated by reference
                                      herein).*

                        4.2           Amended and Restated By-Laws of the
                                      Registrant (filed as Exhibit 3.1 to the
                                      Registrant's Registration Statement on
                                      Form 8-A on September 4, 1998, File No.
                                      000-22667 (98704715), and incorporated by
                                      reference herein).*

                        4.3           1997 Equity Incentive Plan, as amended, of
                                      the Registrant (filed as Exhibit 10.1 to
                                      the Registrant's Quarterly Report on Form
                                      10-Q on November 14, 2001, File No. 000-
                                      22667 and incorporated be reference
                                      herein).*

                        4.4           Certificate of Designation specifying the
                                      terms of the Series A Junior Participating
                                      Preferred Stock of the Registrant (filed
                                      as Exhibit 3.2 to the Registrant's
                                      Registration Statement on Form 8-A on
                                      September 4, 1998, File No. 000-22667
                                      (98704715), and incorporated by reference
                                      herein).*

                        4.5           Rights Agreement dated September 2, 1998
                                      between the Registrant and the Bank of New
                                      York (filed as Exhibit 3.3 to the
                                      Registrant's Registration Statement on
                                      Form 8-A on September 4, 1998, File No.
                                      000-22667 (98704715), and incorporated by
                                      reference herein).*

                        5.1           Opinion of Testa, Hurwitz & Thibeault,
                                      LLP.**

                       23.1           Consent of Testa, Hurwitz & Thibeault, LLP
                                      (contained in its opinion as Exhibit 5.1).

                       23.2           Consent of KPMG, LLP.**

                       24.1           Power of Attorney (included as part of the
                                      signature page of this Registration
                                      Statement).

          *Not-filed herewith. In accordance with Rule 411 promulgated pursuant
to the Securities Act of 1933, as amended, reference is made to the documents
previously filed with the commission, which are incorporated by reference
herein.
          **Filed herewith.

     Item 9. Undertakings.
             -------------

            (a)  The undersigned Registrant hereby undertakes:

                 (1)   To file, during any period in which offers or sales are
                       being made, a post-effective amendment to this
                       Registration Statement:
(i)   To include any prospectus required by Section 10(a)(3)
                          of the Securities Act of 1933;

                    (ii)  To reflect in the prospectus any facts or events
                          arising after the effective date of the Registration
                          Statement (or the most recent post-effective amendment
                          thereof) which, individually or in the aggregate,
                          represent a fundamental change in the information set
                          forth in the Registration Statement; and

                    (iii) To include any material information with respect to
                          the plan of distribution not previously disclosed in
                          the Registration Statement or any material change to
                          such information in the Registration Statement;

                    provided however, that paragraphs (a) (1) (i) and (a) (1)
                    (ii) do not apply if the registration statement is on Form
                    S-3, Form S-8 or Form F-3, and the information required to
                    be included in a post-effective amendment by those
                    paragraphs is contained in periodic reports filed with or
                    furnished to the Commission by the registrant pursuant to
                    Section 13 or 15 (d) of the Securities Exchange Act of 1934
                    that are incorporated by reference in the registration
                    statement.

          (2)       That, for the purpose of determining any liability under the
                    Securities Act of 1933, each such post-effective amendment
                    shall be deemed to be a new registration statement relating
                    to the securities offered therein, and the offering of such
                    securities at that time shall be deemed to be the initial
                    bona fide offering thereof.

          (3)       To remove from registration by means of a post-effective
                    amendment any of the securities being registered which
                    remain unsold at the termination of the offering.

     (b)  The undersigned Registrant hereby undertakes that, for purposes of
          determining any liability under the Securities Act of 1933, each
          filing of the Registrant's annual report pursuant to Section 13(a) or
          Section 15(d) of the Securities Exchange Act of 1934 (and, where
          applicable, each filing of any employee benefit plan's annual report
          pursuant to Section 15(d) of the Securities Exchange Act of 1934) that
          is incorporated by reference in the Registration Statement shall be
          deemed to be a new registration statement relating to the securities
          offered therein, and the offering of such securities at that time
          shall be deemed to be the initial bona fide offering thereof.

     (c)  Insofar as indemnification for liabilities arising under the
          Securities Act of 1933 may be permitted to directors, officers and
          controlling persons of the Registrant pursuant to the foregoing
          provisions, or otherwise, the Registrant has been advised that in the
          opinion of the Securities and Exchange Commission such indemnification
          is against public policy as expressed in the Act and is, therefore,
          unenforceable.  In the event that a claim for indemnification against
          such liabilities (other than the payment by the Registrant of expenses
          incurred or paid by a director, officer or controlling person of the
          Registrant in the successful defense of any action, suit or
          proceeding) is asserted by such director, officer or controlling
          person in connection with the securities being registered, the
          Registrant will, unless in the opinion of its counsel the matter has
          been settled by controlling precedent, submit to a court of
          appropriate jurisdiction the question whether such indemnification by
          it is against public policy as expressed in the Act and will be
          governed by the final adjudication of such issue.
SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Wilton, the State of Connecticut, on this 15/th/ day
of November 2001.

                             MERCATOR SOFTWARE, INC.

                             By: /s/ Roy C. King
                                 -----------------------------------------------
                                 Roy C. King
                                 President, Chief Executive Officer and Chairman

                               POWER OF ATTORNEY

     EACH SUCH PERSON WHOSE SIGNATURE appears below constitutes and appoints,
jointly and severally, Roy C. King and Kenneth Hall and each of them, with full
power to act without the other, his true and lawful attorney-in-fact and agent,
with the power of substitution and resubstitution, for him and in his name,
place and stead, in any and all capacities, to sign any amendments to this
Registration Statement on Form S-8 (including post-effective amendments) and to
file the same, with all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, hereby ratifying and
confirming all that said attorney-in-fact, or his or her substitute or
substitutes, may do or cause to be done by virtue hereof.

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the date indicated.
Signature                                Title                                   Date
             ---------                                -----                                   ----
/s/ Roy C. King                       President, Chief Executive Officer                November 15, 2001
------------------------------------  and Chairman of the Board of Directors
  Roy C. King

/s/ Kenneth Hall                      Sr. Vice President, Chief Financial               November 15, 2001
------------------------------------  Officer and Treasurer
  Kenneth Hall

/s/ James P. Schadt                   Vice-Chairman of the Board of                     November 15, 2001
------------------------------------  Directors
  James P. Schadt

/s/ Diane P. Baker                    Director                                          November 15, 2001
------------------------------------
  Diane P. Baker

/s/ Constance F. Galley               Director                                          November 15, 2001
------------------------------------
  Constance F. Galley

/s/ Ernest E. Keet                    Director                                          November 15, 2001
------------------------------------
  Ernest E. Keet

/s/ Richard Little                    Director                                          November 15, 2001
------------------------------------
  Richard Little

/s/ Dennis G. Sisco                   Director                                          November 15, 2001
------------------------------------
  Dennis G. Sisco

/s/ Mark C. Stevens                   Director                                          November 15, 2001
------------------------------------
  Mark C. Stevens
INDEX TO EXHIBITS

     Exhibit                            Description of Exhibit
     -------                            ----------------------

        4.1              Amended and Restated Certificate of Incorporation, as
                         amended, of the Registrant (filed as Exhibit 3.1 to the
                         Registrant's Quarterly Report on Form 10-Q on November
                         14, 2000, File No. 000-22667 (7674707) and incorporated
                         by reference herein).*

        4.2              Amended and Restated By-Laws of the Registrant (filed
                         as Exhibit 3.1 to the Registrant's Registration
                         Statement on Form 8-A on September 4, 1998, File No.
                         000-22667 (98704715), and incorporated by reference
                         herein).*

        4.3              1997 Equity Incentive Plan, as amended, of the
                         Registrant (filed as Exhibit 10.1 to the
                         Registrant's Quarterly Report on Form 10-Q on November
                         14, 2001, File No. 000-22667 and incorporated be
                         reference herein).*

        4.4              Certificate of Designation specifying the terms of the
                         Series A Junior Participating Preferred Stock of the
                         Registrant (filed as Exhibit 3.2 to the Registrant's
                         Registration Statement on Form 8-A on September 4,
                         1998, File No. 000-22667 (98704715), and incorporated
                         by reference herein).*

        4.5              Rights Agreement dated September 2, 1998 between the
                         Registrant and the Bank of New York (filed as Exhibit
                         3.3 to the Registrant's Registration Statement on Form
                         8-A on September 4, 1998, File No. 000-22667
                         (98704715), and incorporated by reference herein).*

        5.1              Opinion of Testa, Hurwitz & Thibeault, LLP.**

       23.1              Consent of Testa, Hurwitz & Thibeault, LLP (contained
                         in its opinion as Exhibit 5.1).

       23.2              Consent of KPMG, LLP.**

       24.1              Power of Attorney (included as part of the signature
                         page of this Registration Statement).

   *Not-filed herewith. In accordance with Rule 411 promulgated pursuant to the
Securities Act of 1933, as amended, reference is made to the documents
previously filed with the commission, which are incorporated by reference
herein.
   **Filed herewith.