<Page>

                                                                    Exhibit 10.2

          Confidential Materials omitted and filed separately with the
         Securities and Exchange Commission. Asterisks denote omissions.

                                 AMENDMENT NO. 1

        This Amendment (this "AMENDMENT"), dated as of December 23, 2004, hereby
amends the Purchase and Sale Agreement (the "Agreement"), dated as of October 6,
2004, by and among Aspen Technology, a Delaware corporation ("ASPENTECH"),
Hyprotech Company, a limited liability company organized under the laws of Nova
Scotia, Canada ("HYPROTECH"), AspenTech Canada Ltd., a corporation organized
under the laws of Alberta, Canada ("ASPENTECH CANADA"), AspenTech Ltd., a
limited liability company organized under the laws of England ("ASPENTECH UK"),
Hyprotech UK Ltd., a limited liability company organized under the laws of
England ("HYPROTECH UK", AspenTech, Hyprotech, AspenTech Canada and AspenTech
UK, individually and collectively, the "SELLER"), and Honeywell International
Inc., a Delaware corporation ("HONEYWELL"), Honeywell Control Systems Limited, a
company organized under the laws of the United Kingdom ("HONEYWELL CONTROL"),
and Honeywell Limited-Honeywell Limitee, a Canadian company ("HONEYWELL
LIMITED", Honeywell, Honeywell Control and Honeywell Limited, individually and
collectively, the "BUYER"). Capitalized terms used herein and defined in the
Agreement shall have the meanings defined therein unless otherwise defined
herein.

        WHEREAS, the parties to the Agreement desire to amend certain terms of
the Agreement in accordance with the terms of this Amendment;

        NOW THEREFORE, in consideration of the premises and of the mutual
covenants contained herein, the receipt and sufficiency of which is hereby
acknowledged, the parties hereto hereby agree as follows:

        1.      Section 1.1(a)(ii) of the Agreement is hereby amended and
replaced in its entirety with the following:

                "the latest version of research and development work product
                (analyses, prototype, presentations, etc.) comprising the
                Hyprotech project known as "Genesis" (the "GENESIS PROJECT
                MATERIALS") as of the Closing Date and all Intellectual Property
                Rights embodied therein (the "GENESIS IP"), but excluding any
                software relating to Seller software products other than
                Hyprotech Products and Operator Training Products and any
                interfaces to such software products and all Intellectual
                Property Rights embodied in such software and interfaces; the
                software code included in the Genesis Project Materials is
                prototype software, not suitable and untested for commercial
                release, principally consisting of three modules:

<Page>

                "Snoopy", which is a data layer that manages the data models of
                various components, "ProSIM", which is an engineering framework
                layered on top of Snoopy that provides the framework for
                housing, integrating and solving engineering models and includes
                mathematical solvers and other related calculation components,
                and "OpenForms", which is a user interface component for
                interacting with Genesis. The Genesis Project Materials also
                include ProSIM's engineering models, but exclude any engineering
                models and mathematical solvers contained in Seller software
                products (other than Hyprotech Products and Operator Training
                Products) and any third party software."

        2.      Section 1.1(a)(vi) of the Agreement is hereby amended and
replaced in its entirety with the following:

                "(vi)   for material that relates solely to the OTS Business,
                (A) all marketing and sales materials used by Seller anywhere in
                the world, including, but not limited to, all advertising
                materials, training materials (including all electronic files of
                training materials), sales materials (including product data,
                price lists, and mailing lists), promotional and marketing
                materials, marketing information, educational materials,
                competitor information (including research data, market
                intelligence reports, and statistical programs), customer
                information (including customer sales information, customer
                lists, customer files, customer contact information, and
                customer support log data bases), sales forecasting models,
                Website content, and advertising and display materials; and (B)
                all project repositories that are currently in the possession or
                under the control of Seller or its Affiliates for current and
                past projects of the OTS Business (the "PROJECT REPOSITORIES"),
                including [**] without limitation, customer requests, proposals,
                schedules, purchase orders, detailed functional specifications,
                model design documents, factory acceptance test documents,
                steady-state simulations, customer information provided as a
                basis for design and all other project artifacts (the materials
                in clauses (A) and (B), collectively, the "OTS RECORDS");
                PROVIDED, HOWEVER, that (1) Seller may retain a copy of such
                material to the extent necessary for tax, accounting, or legal
                purposes, including as required by applicable laws and
                regulations, or as required in connection with Seller's
                rendering of services for any projects under Retained OTS
                Contracts or Assigned OTS Contracts for which customer consent
                is not obtained, or otherwise in connection with Seller's
                obligations under the Ancillary Agreements (including the
                Subcontract Agreement); and (2) in no event shall Buyer use, or
                allow the use of, any Project Repository or any purpose, except
                to support, develop, maintain or enhance the customer

                                        2
<Page>

                project of Buyer's OTS Business to which such Project Repository
                pertains and (3) Buyer shall not disclose or otherwise make
                available the information or materials in the Project
                Repositories to any person outside of the Buyer's OTS Business
                as of the Closing except that Buyer shall be permitted to
                disclose or otherwise make available such information and
                materials to persons within Buyer's OTS Business (regardless of
                whether they were in the OTS Business as of the Closing) if such
                disclosure is authorized by the customer."

        3.      Section 1.1(c)(ii) of the Agreement is hereby amended and
replaced in its entirety with the following:

                "(ii)   all liabilities and obligations in respect of the
Engineering Software Assets incurred by Buyer after the Closing Date and all
liabilities and obligations of the Buyer and its Affiliates (but not of Seller
and its Affiliates) arising from the receipt, use or [**], except in each case,
to the extent arising out of (A) the ownership or use of the Engineering
Software Assets or operation of the Business on or prior to the Closing Date or
(B) Seller's use after the Closing Date of the Engineering Software Assets under
the Ancillary Agreements;"

        4.      The parties acknowledge and agree that as of the Closing, the
parties have an Unresolved Dispute with respect to the currency exchange rates
used to calculate certain of the Net Unbilled Accounts Receivable, which
Unresolved Dispute could equal up to a maximum amount of $150,000 (the "Currency
Exchange Rate Unresolved Dispute"), and, accordingly, the parties do not agree
on the amount of such Net Unbilled Accounts Receivable, as set forth in more
detail on the Closing Statement created by the parties pursuant to Section
1.2(b)(ii) of the Agreement. Notwithstanding Section 1.2(b)(iii) of the
Agreement, the parties acknowledge and agree that the Purchase Price at Closing
shall be paid as if the parties had agreed upon the Net Unbilled Accounts
Receivable prior to Closing and as if there were no Unresolved Dispute;
provided, however, that, neither anything herein, nor the payment of the
Purchase Price at Closing, shall be deemed to be a waiver by either party of
such Currency Exchange Rate Unresolved Dispute or a resolution of such Currency
Exchange Rate Unresolved Dispute. The parties shall cooperate to resolve such
Currency Exchange Rate Unresolved Dispute within 30 days after Closing and
adjust the Purchase Price, as applicable, at the time of such resolution. In no
event shall the Purchase Price be (i) adjusted downward by more than $150,000
with respect to such Currency Exchange Rate Unresolved Dispute or (ii) adjusted
upwards with respect to such Currency Exchange Rate Unresolved Dispute (the
"LIMITATIONS"). For avoidance of doubt, the parties acknowledge and agree that
the Limitations shall not act as a limitation on either party's recovery
pursuant to the terms of the Agreement with respect to any Purchase Price
adjustment dispute other than the Currency Exchange Rate Unresolved Dispute. If
such Currency Exchange Rate Unresolved Dispute is not resolved by the Holdback
Release Date, the Currency Exchange Rate Unresolved Dispute shall be resolved as
part of the final determination of the Purchase Price adjustment pursuant to
Section 1.2(b)(iv) of the Agreement.

                                        3
<Page>

        5.      Section 1.3(b)(xvii) of the Agreement is hereby amended and
replaced in its entirety with the following:

                "(xvii) the Seller shall deliver (or cause to be delivered) to
                the Buyer, or otherwise put the Buyer in possession and control
                of, all of the Engineering Software Assets of a tangible nature,
                including delivery of license keys, dongles or other security
                devices necessary for Buyer to use and access such Engineering
                Software Assets; provided, however, that:

                (A)     with respect to the Hyprotech Products, Seller shall
        only be obligated to deliver (or cause to be delivered) to the Buyer, or
        otherwise put the Buyer in possession and control of, (1) at Closing,
        (x) the source code for the current commercial version of the Hyprotech
        Products (the "CURRENT HYPROTECH RELEASE"), and (y) the source code for
        each other version that was commercially released by Seller at any time
        during the three-year period prior to the Closing (the "PAST HYPROTECH
        RELEASES", and together with the Current Hyprotech Release, the
        "HYPROTECH CODE DELIVERED AT CLOSING") and (2) after Closing, as set
        forth in this Agreement, including, without limitation, in Section
        10.14; and

        (B) Seller shall have no obligation to deliver DISTIL at Closing [**].

        (C)     Seller shall have [**] delivered to Buyer at Closing [**].
Notwithstanding the foregoing, the Seller shall [**] and shall have [**]. Buyer
understands and agrees that Seller [**]. Seller shall [**]; and

        (D)     Seller shall have [**] Operator Training Products [**]. [**]
Seller does not [**] to Buyer [**], and that Buyer shall be solely
responsible for [**]. Seller shall use commercially reasonable efforts to
include information with the delivery of the Operator Training Products [**].

        (E)     Seller shall have [**] under this Agreement [**]; and

        (F)     Notwithstanding anything herein, [**].

                                        4
<Page>

        6.      Subsection (xx) is hereby added to Section 1.3(b) of the
Agreement:

                "(xx)   At or prior to Closing, Seller shall have delivered to
                the Buyer in electronic format the information contained in
                Seller's customer support knowledge database, to the extent
                related to the Business."

        7.      Section 4.12 of the Agreement is hereby amended and replaced in
its entirety with the following:

                "4.12   HARWELL MATH LIBRARY. On or prior to Closing, Seller
                shall have sublicensed to Buyer the rights under an
                Incorporation License (in form and substance mutually agreed by
                Seller and Buyer) for specified subroutine packages of the
                Harwell Sub-Routine Library, pursuant to the Agreement, dated as
                of April 13, 2004, as amended (the "HARWELL MATH LIBRARY
                AGREEMENT"), between Hyprotech UK Limited and the Council for
                the Central Laboratory of the Research Councils ("CCLRC"); [**]

        8.      Section 9.6(c) is added to the Agreement as follows:

                "Within a reasonable period of time after the Closing Date, but
                no later than ninety (90) days after a Transferred Employee
                submits a list of requested items pursuant to the guidelines set
                forth in SECTION 9.6(c) attached hereto, Seller shall deliver to
                the Buyer the individual work files of the Transferred Employees
                to the extent containing information in the possession of the
                Seller as of Closing related to the OTS Business and/or the
                Hyprotech Products, subject to applicable law and the guidelines
                set forth in SCHEDULE 9.6(c) attached hereto."

        9       Sections 10.17, 10.18, 10.19, 10.20 and 10.21 are added to the
Agreement as follows:

                "10.17  [**]. Buyer agrees that [**] to the [**] under the [**].

                10.18   CUSTOMER-OWNED EQUIPMENT. Buyer acknowledges and agrees
                that the equipment set forth on SCHEDULE 10.18 is owned by the
                applicable third party customer of Seller whose name corresponds
                to such equipment on SCHEDULE 10.18 ("CUSTOMER-OWNED
                EQUIPMENT"), and that all Customer-Owned Equipment is held by
                Seller pursuant to the terms and conditions of the applicable
                Assigned Contract disclosed to Buyer as of the date hereof.
                Seller agrees to transfer to Buyer custody of the Customer-Owned
                Equipment as soon as reasonably practicable after Closing. Buyer
                agrees that, unless otherwise agreed to with the customer owning
                such Customer-Owned Equipment, (a) it shall not use or allow

                                        5
<Page>

                the use of any item of Customer-Owned Equipment other than for
                the purpose of delivering Operator Training Services to the
                customer that is the owner of such equipment pursuant to the
                applicable Assigned Contract (or any amendment or renewal
                thereof), (b) Buyer shall comply will all of the terms and
                conditions of the applicable Assigned Contract with respect to
                the Customer-Owned Equipment, (c) Buyer shall, upon completion
                of a project or otherwise at any time upon request of a
                customer, promptly return to such customer any Customer-Owned
                Equipment owned thereby, and (d) Buyer shall bear the risk of
                loss for any loss or damage to such Customer-Owned Equipment
                from and after its receipt of possession thereof until such time
                as such equipment is returned to the applicable customer.

                10.19   CUSTOMER INFORMATION. Seller shall use commercially
                reasonable efforts to transfer to Buyer all tangible information
                in the possession of Seller that was received by Seller from
                customers pursuant to Assigned Contracts or Retained Contracts
                under which services are subcontracted to Buyer ("CUSTOMER
                INFORMATION"). Buyer agrees that unless otherwise agreed to with
                the applicable customer, (a) in no event shall Buyer use, or
                allow the use of, any Customer Information for any purpose,
                except to support, develop, maintain or enhance the customer
                project of Buyer's OTS Business for which such information was
                initially disclosed to Seller, (b) Buyer shall not disclose or
                otherwise make available the Customer Information to any person
                outside of the Buyer's OTS Business as of the Closing, (c) upon
                completion of its obligations in connection with a project
                (including warranty and support obligations), Buyer shall return
                or destroy the Customer Information initially received by Seller
                for such project, and (d) Buyer shall strictly comply with all
                of the terms and conditions applicable to Seller under each
                Assigned Contract or Retained Contract pursuant to which Seller
                initially received the Customer Information.

                10.20 [**]. Buyer shall [**] unless [**] for the [**]. Buyer
                acknowledges that [**], Seller shall [**] under such license.
                [**] during such period, [**], Seller shall [**].


                10.21 [**]. Seller is [**]. The parties acknowledge and agree
                that [**] Buyer shall have [**] pursuant to the [**], provided
                that [**] under such arrangement, [**]."

        10.     The Disclosure Schedules of the Seller referenced in the
introductory paragraph of Article II are hereby amended and replaced in their
entirety with the Disclosure Schedules set forth in Exhibit A hereto. Buyer
hereby waives any claim or action against the Seller under the Purchase
Agreement that it may have arising from any missing or incomplete information in
the Disclosure Schedules as attached to the Purchase Agreement as of the signing
of such agreement if and to the extent that such missing or incomplete
information is included or completed, as applicable, in the Disclosure Schedules
attached in Exhibit A hereto.

                                        6
<Page>

        11.     This Amendment, together with the Agreement, constitute the
entire agreement between the parties hereto relating to the subject matter
hereof, and shall not be amended or modified, nor may compliance with any
condition or covenant set forth herein be waived, except by a writing duly and
validly executed by the Parties, or in the case of a waiver, the Party or
Parties waiving compliance.

        12.     Whenever possible, each provision of this Amendment shall be
interpreted in such a manner as to be effective and valid under applicable law,
but if any provision of this Amendment shall be deemed prohibited or invalid
under such applicable law, such provision shall be ineffective to the extent of
such prohibition or invalidity, and such prohibition or invalidity shall not
invalidate the remainder of such provision or the other provisions of this
Amendment.

        13.     For convenience of the parties and to facilitate execution, this
Agreement may be executed in two or more counterparts, each of which shall be
deemed an original, but all of which shall constitute one and the same document.

                                        7
<Page>

        IN WITNESS WHEREOF, this Amendment has been signed by or on behalf of
each of the parties hereto, all as of the date first above written.

<Table>
<S>                                               <C>
BUYER:                                            SELLER:


HONEYWELL INTERNATIONAL INC.                      ASPEN TECHNOLOGY, INC.


By:       /s/John R. Ethier                       By:       /s/Charles Kane
   -------------------------------                   ---------------------------------
   Name:  John R. Ethier                             Name:  Charles Kane
   Title: V.P. CFO                                   Title: Interim CEO and CFO


HONEYWELL CONTROL SYSTEM LIMITED                  HYPROTECH COMPANY


By:       /s/John R. Ethier                       By:       /s/D. E. Moult
   -------------------------------                   ---------------------------------
   Name:  John R. Ethier                             Name:  D. E. Moult
   Title: V.P. CFO                                   Title: CFO


HONEYWELL LIMITED - HONEYWELL                     ASPENTECH CANADA LTD.
LIMITEE


By:       /s/John R. Ethier                       By:       /s/ Stephen J. Doyle
   -------------------------------                   ---------------------------------
   Name:  John R. Ethier                             Name:  Stephen J. Doyle
   Title: V.P. CFO                                   Title: Director


                                                  ASPENTECH LTD.


                                                  By:       /s/ Charles Kane
                                                     ---------------------------------
                                                     Name:  Charles Kane
                                                     Title: Director


                                                  HYPROTECH UK, LTD.


                                                  By:       /s/ Stephen J. Doyle
                                                     ---------------------------------
                                                     Name:  Stephen J. Doyle
                                                     Title: Director
</Table>

                                        8
<Page>

                                        9
<Page>

                                    EXHIBIT A

                              DISCLOSURE SCHEDULES


                                [To be provided.]