<PAGE>
 
                                                                   Exhibit 3.1

                  RESTATED CERTIFICATE OF INCORPORATION OF
                          ASPECT DEVELOPMENT, INC.

     The undersigned, Romesh Wadhwani, Chief Executive Officer, and William
Feichtmann, Secretary, of Aspect Development, Inc., a corporation organized and
existing under the laws of the State of Delaware (the "Corporation"), do hereby
certify:

     The date of filing of the Corporation's original Certificate of
Incorporation was March 26, 1993.  This Restated Certificate of Incorporation
was duly adopted by the board of directors, without a vote of the stockholders,
in the manner and by the vote prescribed by Section 245(c) of the Delaware
General Corporation Law and that the following provisions only restate and
integrate and do not further amend, the provisions of the Aspect Development,
Inc. Certificate of Incorporation.

The Certificate of Incorporation of the Corporation is amended and restated to
read in its entirety as follows:

     FIRST:    The name of the Corporation is Aspect Development, Inc.
               (hereinafter sometimes referred to as the "Corporation").

     SECOND:   The address of the registered office of the Corporation in the
               State of Delaware is Incorporating Services, Ltd., 15 East North
               Street, in the City of Dover, County of Kent.  The name of the
               registered agent at that address is Incorporating Services, Ltd.

     THIRD:    The purpose of the Corporation is to engage in any lawful set or
               activity for which a corporation may be organized under the
               General Corporation Law of Delaware.

     FOURTH:

         (A)   Classes of Stock.  The Corporation is authorized to issue two
               classes of stock to be designated, respectively, "Common Stock"
               and "Preferred Stock."  The total number of shares which the
               Corporation is authorized to issue is Twenty Two Million
               (22,000,000) shares.  Twenty Million (20,000,000) shares shall be
               Common Stock, $0.001 par value per share, and Two Million
               (2,000,000) shares shall be Preferred Stock, $0.001 par value per
               share.

         (B)   Rights, Preferences and Restrictions of Preferred Stock.  The
               Stock authorized by this Certificate of Incorporation may be
               issued from time to time in one or more series.  The Board of
               Directors is authorized to determine, alter or eliminate any or
               all of the rights, preferences, privileges and restrictions
               granted to or imposed upon any wholly unissued series of
               Preferred Stock, and to fix, increase or decrease the number of
               shares 
<PAGE>
 
               comprising any such series (but not below the number of such
               shares then outstanding) and the designation thereof, or any of
               them, and to provide for the rights and terms of redemption or
               conversion of the shares of any such series.

          (C)  Common Stock:

               1.   Dividend Rights.  Subject to the prior rights of holders of
                    all classes of stock at the time outstanding having prior
                    rights as to dividends, holders of the Common Stock shall be
                    entitled to receive, when and as declared by the Board of
                    Directors, out of any assets of the Corporation legally
                    available therefor, such dividends as may be declared from
                    to time by the Board of Directors.

               2.   Liquidation Rights.  Subject to the prior rights of holders
                    of all classes of stock at the time outstanding, upon the
                    liquidation, dissolution or winding up of the Corporation,
                    the assets of the Corporation shall be distributed pro rata
                    among the holders of Common Stock.

               3.   Redemption.  The Common Stock is not redeemable.

               4.   Voting Rights.  The holder of each share of Common Stock
                    shall have the right to one vote, and shall be entitled to
                    notice of any stockholders' meeting in accordance with the
                    Bylaws of the Corporation, and shall be entitled to vote
                    upon such matters and in such manner as may be provided by
                    law.

     FIFTH:    The business and affairs of the Corporation shall be managed by
               or under the direction of the Board of Directors. In addition
               to the powers and authority expressly conferred upon them by
               statute or by this Certificate of Incorporation or the Bylaws
               of the Corporation, the directors are hereby empowered to
               exercise all such powers and do all such acts and things as may
               be exercised or done by the Corporation. Election of directors
               need not be by written ballot, unless the Bylaws so provide.

     SIXTH:    The Board of Directors is authorized to make, adopt, amend, alter
               or repeal the Bylaws of the Corporation; provided that any
               amendment, alteration or repeal of the Corporation's Bylaws which
               would increase or decrease the authorized number of directors
               shall be approved by not less than that number of directors as
               shall equal the then authorized number of directors, minus one.
               The stockholders shall also have power to make, adopt, amend,
               alter or repeal the Bylaws of the corporation.

     SEVENTH:  The Corporation reserves the right to amend or repeal any of the
               provisions contained in this Certificate of Incorporation in any
               manner now or hereafter permitted by law, and the rights of the
               stockholders of the Corporation are granted subject to this
               reservation.
<PAGE>
 
     EIGHTH:   To the fullest extent permitted by the Delaware General
               Corporation Law, a director of the Corporation shall not be
               liable to the Corporation or its Stockholders for monetary
               damages for breach of fiduciary duty as a director.  Any repeal
               or modification of the foregoing provisions of this Article EIGHT
               by the stockholders of the Corporation shall not adversely affect
               any right or protection of a director of the Corporation existing
               at the time of such repeal or modification.

     IN WITNESS WHEREOF, the Corporation has caused this Restated Certificate of
Incorporation to be signed by its President and attested by its Secretary this
18th day of September, 1996.

                                    /s/ Romesh Wadhwani
                                    -------------------
                                    Romesh Wadhwani, President

Attest:

/s/ William Feichtmann
----------------------
William Feichtmann, Secretary
<PAGE>
 
                               CERTIFICATE OF
                                AMENDMENT OF
                            AMENDED AND RESTATED
                       CERTIFICATE OF INCORPORATION OF
                          ASPECT DEVELOPMENT, INC.

     Romesh Wadhwani and William Feichtmann, Hereby Certify That:

     First:  They are the duly elected and acting Chief Executive Officer and
Secretary, respectively, of Aspect Development, Inc., a Delaware corporation.

     Second:  The name of this corporation is Aspect Development, Inc. (the
"Corporation").

     Third:  The date on which the Certificate of Incorporation of the
Corporation was originally filed with the Secretary of State of the State of
Delaware (the "Secretary of State") is March 26, 1993.  The date on which the
Certificate of Amendment of Amended and Restated Certificate of Incorporation
was filed with the Secretary of State is May 1, 1996.

     Fourth:  The amendment to the Corporation's Amended and Restated
Certificate of Incorporation set forth below was duly adopted by the Board of
Directors of the Corporation, and approved by the Stockholders in accordance
with the provisions of Section 242 of the General Corporation Law of the State
of Delaware.

     Fifth:  The Section titled "Fourth" of the Corporation's Amended and
Restated Certificate of Incorporation is amended to read in its entirety as
follows:

     "(A)  Classes of Stock. The Corporation is authorized to issue two
           classes of stock to be designated, respectively, "Common Stock" and
           "Preferred Stock." The total number of shares which the Corporation
           is authorized to issue is One Hundred Two Million (102,000,000)
           shares. One Hundred Million (100,000,000) shares shall be Common
           Stock, $0.001 par value per share, and Two Million (2,000,000)
           shares shall be Preferred Stock, $0.001 par value per share.

     (B)   Rights, Preferences and Restrictions of Preferred Stock. The
           Preferred Stock authorized by this Certificate of Incorporation may
           be issued from time to time in one or more series. The Board of
           Directors is authorized to determine, alter or eliminate any or all
           of the rights, preferences, privileges and restrictions granted to
           or imposed upon any wholly unissued series of Preferred Stock, and
           to fix, increase or decrease the number of shares comprising any
           such series (but not below the number of such shares then
           outstanding) and the designation thereof, or any of them, and to
           provide for the rights and terms of redemption or conversion of the
           shares of any such series.

     (C)   Common Stock.

           1.   Dividend Rights. Subject to the prior rights of holders of all
                classes of stock at the time outstanding having prior rights
                as to dividends, the 
<PAGE>
 
                holders of the Common Stock shall be entitled to receive, when
                and as declared by the Board of Directors, out of any assets
                of the Corporation legally available therefor, such dividends
                as may be declared from time to time by the Board of
                Directors.

          2.    Liquidation Rights. Subject to the prior rights of holders of
                all classes of stock at the time outstanding, upon the
                liquidation, dissolution or winding up of the Corporation, the
                assets of the Corporation shall be distributed pro rata among
                the holders of Common Stock.

          3.    Redemption.  The Common Stock is not redeemable.

          4.    Voting Rights.  The holder of each share of Common Stock shall
                have the right to one vote, and shall be entitled to notice of
                any stockholders' meeting in accordance with the Bylaws of the
                Corporation, and shall be entitled to vote upon such matters and
                in such manner as may be provided by law."


     In Witness Whereof, the undersigned have signed this Certificate of
Amendment of Amended and Restated Certificate of Incorporation this 31st day of
July, 1998, and hereby affirm and acknowledge under penalty of perjury that the
filing of this Certificate of Amendment and Amended and Restated Certificate of
Incorporation of Aspect Development, Inc. is the act and deed of Aspect
Development, Inc.

                              Aspect Development, Inc.



                              By:    /s/ Romesh Wadhwani
                                  -------------------------------------------
                                     Romesh Wadhwani, Chief Executive Officer

Attest:

/s/ William Feichtman
-----------------------------
William Feichtmann, Secretary
<PAGE>
 
                         Certificate of Designation

                                     of

                Series A Junior Participating Preferred Stock

                       (Pursuant to Section 151 of the
                      Delaware General Corporation Law)

     ASPECT DEVELOPMENT, INC., a corporation organized and existing under the
General Corporation Law of the State of Delaware (hereinafter called the
"Company"), hereby certifies that the following resolution was adopted by the
Board of Directors of the Corporation as required by Section 151 of the General
Corporation Law at a meeting of the Board of Directors which occurred on
September 1, 1998:

          Resolved, that pursuant to the authority granted to and vested in the
          Board of Directors of the Company in accordance with the provisions of
          its Restated Certificate of Incorporation, the Board of Directors
          hereby creates a series of Preferred Stock, par value $.001 per share,
          of the Company and hereby states the designation and number of shares,
          and fixes the relative designations and the powers, preferences and
          rights, and the qualifications, limitations and restrictions thereof
          (in addition to the provisions set forth in the Certificate of
          Incorporation of the Company, which are applicable to the Preferred
          Stock of all classes and series), as follows:

          Series A Junior Participating Preferred Stock:

     Section 1. Designation and Amount. Six Hundred Thousand (600,000) shares
of Preferred Stock, $.001 par value, are designated "Series A Junior
Participating Preferred Stock" with the designations and the powers,
preferences and rights, and the qualifications, limitations and restrictions
specified herein (the "Junior Preferred Stock"). Such number of shares may be
increased or decreased by resolution of the Board of Directors; provided, that
no decrease shall reduce the number of shares of Junior Preferred Stock to a
number less than the number of shares then outstanding plus the number of
shares reserved for issuance upon the exercise of outstanding options, rights
or warrants or upon the conversion of any outstanding securities issued by the
Company convertible into Junior Preferred Stock.

     Section 2.  Dividends and Distributions.

            (A)  Subject to the rights of the holders of any shares of any
series of Preferred Stock (or any similar stock) ranking prior and superior to
the Junior Preferred Stock with respect 
<PAGE>
 
to dividends, the holders of shares of Junior Preferred Stock, in preference
to the holders of Common Stock, par value $.001 per share (the "Common
Stock"), of the Company, and of any other junior stock, shall be entitled to
receive, when, as and if declared by the Board of Directors out of funds
legally available for the purpose, quarterly dividends payable in cash on the
first day of April, July, October and January in each year (each such date
being referred to herein as a "Quarterly Dividend Payment Date"), commencing
on the first Quarterly Dividend Payment Date after the first issuance of a
share or fraction of a share of Junior Preferred Stock, in an amount per share
(rounded to the nearest cent) equal to the greater of (a) $l.00 or (b) subject
to the provision for adjustment hereinafter set forth, 100 times the aggregate
per share amount of all cash dividends, and 100 times the aggregate per share
amount (payable in kind) of all non-cash dividends or other distributions,
other than a dividend payable in shares of Common Stock or a subdivision of
the outstanding shares of Common Stock (by reclassification or otherwise),
declared on the Common Stock since the immediately preceding Quarterly
Dividend Payment Date or, with respect to the first Quarterly Dividend Payment
Date, since the first issuance of any share or fraction of a share of Junior
Preferred Stock. In the event the Company shall at any time declare or pay any
dividend on the Common Stock payable in shares of Common Stock, or effect a
subdivision or combination or consolidation of the outstanding shares of
Common Stock (by reclassification or otherwise than by payment of a dividend
in shares of Common Stock) into a greater or lesser number of shares of Common
Stock, then in each such case the amount to which holders of shares of Junior
Preferred Stock were entitled immediately prior to such event under clause (b)
of the preceding sentence shall be adjusted by multiplying such amount by a
fraction, the numerator of which is the number of shares of Common Stock
outstanding immediately after such event and the denominator of which is the
number of shares of Common Stock that were outstanding immediately prior to
such event.

            (B)  The Company shall declare a dividend or distribution on the
Junior Preferred Stock as provided in paragraph (A) of this Section
immediately after it declares a dividend or distribution on the Common Stock
(other than a dividend payable in shares of Common Stock); provided, that in
the event no dividend or distribution shall have been declared on the Common
Stock during the period between any Quarterly Dividend Payment Date and the
next subsequent Quarterly Dividend Payment Date, a dividend of $1.00 per share
on the Junior Preferred Stock shall nevertheless be payable on such subsequent
Quarterly Dividend Payment Date.

            (C)  Dividends shall begin to accrue and be cumulative on
outstanding shares of Junior Preferred Stock from the Quarterly Dividend
Payment Date next preceding the date of issue of such shares, unless the date
of issue of such shares is prior to the record date for the first Quarterly
Dividend Payment Date, in which case dividends on such shares shall begin to
accrue from the date of issue of such shares, or unless the date of issue is a
Quarterly Dividend Payment Date or is a date after the record date for the
determination of holders of shares of Junior Preferred Stock entitled to
receive a quarterly dividend and before such Quarterly Dividend Payment Date,
in either of which events such dividends shall begin to accrue and be
cumulative from such Quarterly Dividend Payment Date. Accrued but unpaid
dividends shall not bear interest. Dividends paid on the shares of Junior
Preferred Stock in an amount less than the total amount of such dividends at
the time accrued and payable on such shares shall be allocated pro rata on a
share-by-share basis among all such shares at the time outstanding. The Board
of Directors may fix a record date for the determination of holders of shares
of Junior Preferred 
<PAGE>
 
Stock entitled to receive payment of a dividend or distribution declared
thereon, which record date shall be not more than 60 days prior to the date
fixed for the payment thereof.

     Section 3.  Voting Rights.  The holders of shares of Junior Preferred Stock
shall have the following voting rights:

            (A)  Subject to the provision for adjustment hereinafter set
forth, each share of Junior Preferred Stock shall entitle the holder thereof
to 100 votes on all matters submitted to a vote of the stockholders of the
Company. In the event the Company shall at any time declare or pay any
dividend on the Common Stock payable in shares of Common Stock, or effect a
subdivision or combination or consolidation of the outstanding shares of
Common Stock (by reclassification or otherwise than by payment of a dividend
in shares of Common Stock) into a greater or lesser number of shares of Common
Stock, then in each such case the number of votes per share to which holders
of shares of Junior Preferred Stock were entitled immediately prior to such
event shall be adjusted by multiplying such number by a fraction, the
numerator of which is the number of shares of Common Stock outstanding
immediately after such event and the denominator of which is the number of
shares of Common Stock that were outstanding immediately prior to such event.

            (B)  Except as otherwise provided herein, in any other Certificate
of Designation creating a series of Preferred Stock or any similar stock, or
by law, the holders of shares of Junior Preferred Stock and the holders of
shares of Common Stock and any other capital stock of the Company having
general voting rights shall vote together as one class on all matters
submitted to a vote of stockholders of the Company.

            (C)  Except as set forth herein, or as otherwise provided by law,
holders of Junior Preferred Stock shall have no special voting rights and
their consent shall not be required (except to the extent they are entitled to
vote with holders of Common Stock as set forth herein) for taking any
corporate action.

     Section 4.  Certain Restrictions.

            (A)  Whenever quarterly dividends or other dividends or
distributions payable on the Junior Preferred Stock as provided in Section 2
are in arrears, thereafter and until all accrued and unpaid dividends and
distributions, whether or not declared, on shares of Junior Preferred Stock
outstanding shall have been paid in full, the Company shall not:

                 (i)   declare or pay dividends, or make any other
distributions, on any shares of stock ranking junior (either as to dividends
or upon liquidation, dissolution or winding up) to the Junior Preferred Stock;

                 (ii)  declare or pay dividends, or make any other
distributions, on any shares of stock ranking on a parity (either as to
dividends or upon liquidation, dissolution or winding up) with the Junior
Preferred Stock, except dividends paid ratably on the Junior Preferred Stock
and all such parity stock on which dividends are payable or in arrears in
proportion to the total amounts to which the holders of all such shares are
then entitled;
<PAGE>
 
                 (iii)  redeem or purchase or otherwise acquire for
consideration shares of any stock ranking junior (either as to dividends or
upon liquidation, dissolution or winding up) to the Junior Preferred Stock,
provided that the Company may at any time redeem, purchase or otherwise
acquire shares of any such junior stock in exchange for shares of any stock of
the Company ranking junior (either as to dividends or upon dissolution,
liquidation or winding up) to the Junior Preferred Stock; or

                 (iv)   redeem or purchase or otherwise acquire for
consideration any shares of Junior Preferred Stock, or any shares of stock
ranking on a parity (either as to dividends or upon liquidation, dissolution
or winding up) with the Junior Preferred Stock, except in accordance with a
purchase offer made in writing or by publication (as determined by the Board
of Directors) to all holders of such shares upon such terms as the Board of
Directors, after consideration of the respective annual dividend rates and
other relative rights and preferences of the respective series and classes,
shall determine in good faith will result in fair and equitable treatment
among the respective series or classes.

           (B)   The Company shall not permit any subsidiary of the Company to
purchase or otherwise acquire for consideration any shares of stock of the
Company unless the Company could, under paragraph (A) of this Section 4,
purchase or otherwise acquire such shares at such time and in such manner.

    Section 5.  Reacquired Shares.  Any shares of Junior Preferred Stock
purchased or otherwise acquired by the Company in any manner whatsoever shall
be retired and cancelled promptly after the acquisition thereof. All such
shares shall upon their cancellation become authorized but unissued shares of
Preferred Stock and may be reissued as part of a new series of Preferred Stock
subject to the conditions and restrictions on issuance set forth herein, in
the Restated Certificate of Incorporation, or in any other Certificate of
Designation creating a series of Preferred Stock or any similar stock or as
otherwise required by law.

    Section 6.  Liquidation, Dissolution or Winding Up.  Upon any liquidation,
dissolution or winding up of the Company, no distribution shall be made (1) to
the holders of shares of stock ranking junior (either as to dividends or upon
liquidation, dissolution or winding up) to the Junior Preferred Stock unless,
prior thereto, the holders of shares of Junior Preferred Stock shall have
received $100 per share, plus an amount equal to accrued and unpaid dividends
and distributions thereon, whether or not declared, to the date of such payment,
provided that the holders of shares of Junior Preferred Stock shall be entitled
to receive an aggregate amount per share, subject to the provision for
adjustment hereinafter set forth, equal to 100 times the aggregate amount to be
distributed per share to holders of shares of Common Stock, or (2) to the
holders of shares of stock ranking on a parity (either as to dividends or upon
liquidation, dissolution or winding up) with the Junior Preferred Stock, except
distributions made ratably on the Junior Preferred Stock and all such parity
stock in proportion to the total amounts to which the holders of all such shares
are entitled upon such liquidation, dissolution or winding up.  In the event the
Company shall at any time declare or pay any dividend on the Common Stock
payable in shares of Common Stock, or effect a subdivision or combination or
consolidation of the outstanding shares of Common Stock (by reclassification or
otherwise than by payment of a dividend in shares of Common Stock) into a
greater or lesser number of shares of Common Stock, then in each such case the
aggregate amount to which holders of shares of Junior 
<PAGE>
 
Preferred Stock were entitled immediately prior to such event under the
proviso in clause (1) of the preceding sentence shall be adjusted by
multiplying such amount by a fraction the numerator of which is the number of
shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

    Section 7.  Consolidation, Merger, etc.  In case the Company shall enter
into any consolidation, merger, combination or other transaction in which the
shares of Common Stock are exchanged for or changed into other stock or
securities, cash and/or any other property, then in any such case each share
of Junior Preferred Stock shall at the same time be similarly exchanged or
changed into an amount per share, subject to the provision for adjustment
hereinafter set forth, equal to 100 times the aggregate amount of stock,
securities, cash and/or any other property (payable in kind), as the case may
be, into which or for which each share of Common Stock is changed or
exchanged. In the event the Company shall at any time declare or pay any
dividend on the Common Stock payable in shares of Common Stock, or effect a
subdivision or combination or consolidation of the outstanding shares of
Common Stock (by reclassification or otherwise than by payment of a dividend
in shares of Common Stock) into a greater or lesser number of shares of Common
Stock, then in each such case the amount set forth in the preceding sentence
with respect to the exchange or change of shares of Junior Preferred Stock
shall be adjusted by multiplying such amount by a fraction, the numerator of
which is the number of shares of Common Stock outstanding immediately after
such event and the denominator of which is the number of shares of Common
Stock that were outstanding immediately prior to such event.

    Section 8.  No Redemption.  The shares of Junior Preferred Stock shall not
be redeemable.

    Section 9.  Rank.  The Junior Preferred Stock shall rank, with respect to
the payment of dividends and the distribution of assets, junior to all series
of any other class of the Company's Preferred Stock.

    Section 10.  Amendment.  The Restated Certificate of Incorporation of the
Company shall not be amended in any manner which would materially alter or
change the powers, preferences or special rights of the Junior Preferred Stock
so as to affect them adversely without the affirmative vote of the holders of
at least two-thirds of the outstanding shares of Junior Preferred Stock,
voting together as a single class.
<PAGE>
 
     In Witness Whereof, the undersigned have executed this certificate as of
October 13, 1998.

                              By:   /s/ David S. Dury
                                  --------------------------------------------
                                    David S. Dury
                                    Vice President and Chief Financial Officer

                              By:   /s/ William H. Feichtmann
                                  --------------------------------------------
                                    William H. Feichtmann
                                    Secretary