<PAGE>
 
                                                                  EXHIBIT 10.23
 
                             EMPLOYMENT AGREEMENT
 
  Agreement made as of September 30, 1996, between MAPINFO CORPORATION, One
Global View, Troy, New York 12180 ("MapInfo"), and Michael D. Marvin (MARVIN)
residing at 16 Park Hill, Menands, New York 12204.
 
  1. Engagement. MapInfo agrees to employ MARVIN, and he agrees to serve as
the MapInfo Chairman, and acting President and Chief Executive Officer of the
corporation.
 
  2. Term. The term of this Agreement shall begin on October 1, 1996, and
shall continue until terminated in accordance with any of the following. The
current Agreement shall remain in effect until October 1, 1996.
 
    2.1 This Agreement for services shall terminate after a new Company
  President/CEO has been hired and that person and the Board determined that
  MARVIN's services in the capacity described hereafter are no longer
  required. Upon such termination of full time employment:
 
      2.1.1 While he remains Chairman of the Board, MARVIN may, at his
    option, continue to occupy his office at MapInfo; and
 
      2.1.2 Whether or not MARVIN remains with MapInfo, the Company for a
    period of one year, shall provide MARVIN with full access to, and the
    assistance of Kathy Dinardo; and
 
      2.1.3 Kathy Dinardo and MARVIN have the sole responsibility for
    terminating this relationship before the end of the transition year.
 
    2.2 This Agreement may be terminated by MapInfo at any time for Cause.
  For the purposes of this Agreement, Cause shall be any of the following:
 
      2.2.1 The breach by MARVIN of a material provision of this Agreement,
    including but not limited to the failure of MARVIN to provide the
    services called for hereunder, or any breach by MARVIN of
    confidentiality, or violation of any non-compete agreement; or
 
      2.2.2 Malfeasance in relation to the company; or
 
      2.2.3 Upon the conviction of MARVIN for any crime, or because MapInfo
    reasonably believes MARVIN may have been, or is, involved in criminal
    or other activities of such a nature as could injure the reputation of
    MapInfo.
 
      2.2.4 Material failure to perform his duties which failure is not
    cured within 30 days after notice.
 
    2.3 In the event that MARVIN shall be prevented from performing his
  duties for a continuous period of three (3) months as a result of a
  personal injury, mental or physical disability, or illness, MapInfo may
  terminate this Agreement upon twenty (20) day written notice to MARVIN.
  Salary shall only be continued for ninety (90) days after the date the
  disability commences, reduced dollar for dollar by the amount of any
  disability insurance benefits paid to him by reason of company owned
  disability policies.
 
  3. Services. MARVIN shall devote his best and full-time efforts to
fulfilling his responsibilities to MapInfo. He shall use his individual
expertise to the extend possible for effective financial and administrative
operation of the company, as well as the growth of the business.
<PAGE>
 
  4. Compensation. As compensation for the services to be rendered MapInfo
shall pay and provide the following to MARVIN:
 
    4.1 A base salary for year one at the rate of Two Hundred and fifty
  Thousand Dollars ($250,000.00) per year, and
 
      4.1.2 Bonuses based upon the performance of the Corporation and upon
    MARVIN achieving his targeted company fiscal year objectives as
    established by the Board of Directors in conference with MARVIN, and
    further, upon MARVIN achieving super objectives established by the
    Board of Directors, subject to the following:
 
        4.1.2.1 $125,000 in year one, payable quarterly, for achieving
      targeted company fiscal year objectives, and
 
      4.1.3 Upon signing, MARVIN shall receive 25,000 shares of MapInfo
    stock options vesting March 31, 1997. These options shall remain in
    effect as long as MARVIN is employed by the Company.
 
    4.4 Participation in all employee benefit programs, such as medical
  insurance, retirement and disability programs, as set forth in the MapInfo
  Employee's Manual, and as they may be amended from time to time.
 
  5. Expenses. In addition to the compensation provided for above, MARVIN
shall also be entitled to reimbursement for all reasonable expenses
necessarily incurred by him in the performance of his duties, upon
presentation of vouchers indicating the amount and business purposes.
 
  6. Non-competition. MARVIN shall sign the annexed non-compete agreement as a
condition of his employment.
 
  7. Amendment. This Agreement shall be amended only in writing, signed by
MARVIN and MapInfo's Secretary of the Board.
 
  8. Notices. All notices required or permitted to be given under this
Agreement shall be hand delivered or sent by registered or certified mail,
return requested to the last known address of either party.
 
  9. Successors and Assigns. This Agreement shall inure to the benefit of and
be binding upon MapInfo, its successors and assigns, including, without
limitation, any corporation which may acquire all or substantially all of
MapInfo's assets and business or into which MapInfo may be consolidated or
merged, and MARVIN, his heirs, executors, administrators and legal
representatives. MARVIN may assign his right to payment under this Agreement,
but not his obligations under this Agreement.
 
  10. Entire Agreement. This Agreement is the entire Agreement of the parties
regarding the subject matter hereof, and supersedes all prior understandings.
There are no oral agreements or other writings related to the matters set
forth herein.
 
  11. Governing Law. This Agreement shall be governed by the laws of New York
State.
 
MICHAEL D. MARVIN                         MAPINFO CORPORATION
 
 
         /s/ Michael D. Marvin                      /s/ John F. Haller
_____________________________________     By___________________________________
                                                 John F. Haller, Secretary
 
 
                9/30/96
Date: _______________________________                     9/30/96
                                          Date: _______________________________