Document:

<PAGE>

                                                                  EXHIBIT 10.20

                         DEFERRED COMPENSATION AGREEMENT
                                     BETWEEN
                          BENTLEY SYSTEMS, INCORPORATED
                                       AND
                           [                        ]

<PAGE>

                         DEFERRED COMPENSATION AGREEMENT

            THIS AGREEMENT is made as of this 6th day of August, 1999 (the
"Agreement Date") between Bentley Systems, Incorporated, a Delaware corporation
("Employer"), and [_____________________] ("Executive").

            The parties hereto, intending to be legally bound hereby, agree as
follows:

            1.    Deferred Compensation Account.  As of August 6, 1999,
Employer shall establish on its books a Deferred Compensation Account (the
"Account") for Executive, and will credit to such Account an amount equal to
[$           ].

            2. Agreement Unfunded. This Agreement shall be unfunded for tax
purposes and for the purposes of Title I of the Employee Retirement Income
Security Act of 1974, as amended. Executive shall have the status of a general
unsecured creditor of Employer and this Agreement shall constitute a mere
promise by Employer to make payments in the future. Employer may establish a
grantor trust to which general corporate assets may be contributed in order to
assist Employer in meeting its obligation under this Agreement.

            3. Interest on Deferred Amount. Interest on the amount credited to
Executive's Account pursuant to Paragraph 1 shall be paid directly to Executive
on the business day coincident with or first following August 6, 2000 and August
6 of each year (or partial year) of this Agreement thereafter, at the rate of
six percent (6%) per annum, until the amount credited to Executive's Account is
paid in accordance with Paragraph 4 (at which time all accrued but unpaid
interest shall also be paid).

            4. Payment of Deferred Amount

                  (a)   Date Certain.  The amount credited to Executive's
Account shall be paid to Executive in a single lump-sum amount on August 6,
2005.

                  (b) Termination of Employment. In the event Executive's
employment with Employer terminates for any reason (other than death) prior to
the date in subparagraph (a), the amount credited to Executive's Account shall
be paid to Executive in a single lump-sum payment not later than 90 days
following the termination.

                  (c) Death. In the event Executive dies prior to the date in
subparagraph (a), the amount credited to his Account shall be paid to his
surviving

<PAGE>

spouse in a single lump-sum payment not later than 90 days following the date of
death, or, if his spouse has predeceased him or if Executive is otherwise
unmarried at his death, to Executive's estate.

                  (d) Change of Control. In the event of a Change of Control of
Employer, the amount credited to Executive's Account shall be paid to Executive
in a single lump-sum payment not later than 90 days following the Change of
Control. A "Change of Control" shall be deemed to have taken place if:

                        (1) any person or entity, including a "group" (within
      the meaning of Rule 13d-1 under the Securities Exchange Act of 1934, as
      amended (the "Exchange Act")) but excluding Employer or any stockholder of
      Employer as of the date of this Agreement who are part of a "group" that
      controls Employer as of the date hereof, becomes the beneficial owner of
      shares of Employer having 50 percent or more of the total number of votes
      that may be cast for the election of directors of Employer;

                        (2) there occurs any cash tender or exchange offer for
      shares of Employer, merger or other business combination involving
      Employer, or sale of all or substantially all of the assets of Employer,
      or any combination of the foregoing transactions, and as a result of or in
      connection with any such event persons who were directors of Employer
      before the event shall cease to constitute a majority of the Board of
      Directors of Employer or any successor to Employer; or

                        (3) during any period of two consecutive calendar years
      beginning after the date of the initial public offering of the common
      stock of Employer, members of the Incumbent Board cease for any reason to
      constitute a majority of the Board. For this purpose, the "Incumbent
      Board" shall consist of the individuals who at the beginning of such
      period constitute the entire Board and any new director - other than a
      director (i) designated or nominated by, or affiliated with, a person who
      has entered into an agreement with Employer to effect a transaction
      described in (2) above, or (ii) who initially assumed office as result of
      either an actual or threatened "Election Contest" (as described in Rule
      14a-11 under the Exchange Act), or other actual or threatened solicitation
      of proxies or contest by or on behalf of a person other than the Board (a
      "Proxy Contest"), including by reason of any agreement intended to avoid
      or settle any Election Contest or Proxy Contest - whose election by the
      Board or nomination for election by the stockholders of Employer was
      approved by a vote of at least 2/3rds of the directors then still in
      office who either were directors at the beginning of the period or whose
      election or nomination for election was previously so approved.

                        (4) As used in (1), (2), and (3) above, the terms
      "person" and "beneficial owner" have the same meaning as such terms

                                      -2-
<PAGE>

      under Section 13(d) of the Exchange Act and the rules and regulations
      promulgated thereunder.

                  (e) Initial Public Offering. In the event of an initial public
offering of equity securities of Employer which is registered under the
Securities Act of 1933, as amended, the amount credited to Executive's Account
shall be paid to Executive in a single lump-sum payment no later than six months
following the initial public offering.

            5. Amendment or Termination. This Agreement may be amended or
terminated upon the mutual agreement of Employer and Executive.

            6. Withholding; Payroll Taxes. Employer shall withhold from any
payment made under this Agreement any taxes required to be withheld for Federal,
state, or local taxes.

            7. Non-Alienation. No benefits under this Agreement shall be subject
in any manner to anticipation, alienation, sale, transfer, assignment, pledge,
encumbrance, attachment, or garnishment by creditors of Executive or his spouse
or estate, and any attempt to do so shall be void and unenforceable. Such
benefits shall not be subject to or liable for the debts, contracts,
liabilities, engagements, or torts of Executive or his spouse or estate.

            8. General Funds of Employer. Nothing contained in this Agreement
and no action taken pursuant to the provisions of this Agreement shall create or
be construed to create a trust of any kind (except as provided in Paragraph 2),
or a fiduciary relationship between Employer and Executive, his spouse or
estate, or any other person. To the extent that any person acquires a right to
receive payments from Employer under this Agreement, such right shall be no
greater than the right of an unsecured general creditor of Employer.

            9. No Effect on Benefit Plans. No deferred compensation payable
under this Agreement shall be deemed salary or other compensation to Executive
for the purpose of computing benefits to which he may be entitled under any
pension or profit-sharing plan or other arrangement of Employer for providing
benefits to its employees.

            10. Interpretation of Agreement. Employer shall have full power and
authority to interpret, construe, and administer this Agreement. Employer's
interpretation and construction thereof, and actions thereunder, including any
valuation of Executive's Account, or its determination of the amount or
recipient of payments to be made therefrom, shall be binding and conclusive on
all persons for all purposes. Employer shall not be liable to any person for any
action taken or omitted in connection with the interpretation and administration
of this Agreement unless attributable to its own willful misconduct.

                                      -3-
<PAGE>

            11.  Binding Nature.  This Agreement shall be binding upon and
inure to the benefit of Employer, its successors and assigns, and Executive
and his heirs, executors, administrators, and legal representatives.

            12.  Applicable Law.  This Agreement shall be construed in
accordance with and governed by the laws of the Commonwealth of Pennsylvania.

            IN WITNESS WHEREOF, Employer has caused this Agreement to be
executed by its duly authorized officer, and Executive has hereunto set his hand
and seal on the date first above written.

EXECUTIVE                                 BENTLEY SYSTEMS, INCORPORATED

                                          By: /s/ David Nation
-------------------------------              -------------------------------
                                             Senior V.P.

                                      -4-
<PAGE>
                  Schedule of Deferred Compensation Agreements

     The following schedule identifies the individuals that have executed a
Deferred Compensation Agreement, dated August 6, 1999, with Bentley Systems,
Incorporated. The schedule also sets forth the amounts credited to such
individuals' accounts.

<Table>
<Caption>

          Name:                                   Amount Credited
          -----                                   ---------------
<S>                                               <C>
          Barry J. Bentley                        $1,142,221

          Gregory S. Bentley                      $1,142,225

          Keith A. Bentley                        $1,142,221

          Raymond B. Bentley                      $571,111

          Richard P. Bentley                      $571,111

          David G. Nation                         $571,111
</Table><PAGE>
                                                                   Exhibit 10.21

                                 PROMISSORY NOTE

$229,400.00                                                     January 14, 2002

         FOR VALUE RECEIVED, Gregory and Caroline Bentley ("Maker"), hereby
unconditionally promises to pay to the order of Bentley Systems, Incorporated, a
Delaware corporation ("Payee"), on the earlier of January 14, 2007 (the
"Maturity Date"), the date specified in paragraph 5 below or upon the demand of
the holder subsequent to an Event of Default (as defined in the Pledge Agreement
between Maker and Payee of January 14, 2002 (as amended, the "Pledge
Agreement")), the principal amount of Two Hundred Twenty Nine Thousand Four
Hundred and No/100 Dollars ($229,400.00), together with interest on the
outstanding principal balance hereof from time to time outstanding from the date
hereof and until this Note is paid in full, whether before or after maturity, at
the rate of six percent (6%) per annum, and, to the extent lawful, to pay
interest at the same rate on any overdue installment of interest.

1. Interest shall be simple interest calculated on the basis of actual days
elapsed and a year of 365 days and shall be paid at the same time as the
principal amount, or any portion thereof, is paid.

2. Payments of principal and interest shall be made in lawful money of the
United States of America by cash or check at Bentley Systems, Incorporated, 685
Stockton Drive, Exton, PA 19341 or at such other place as the holder of this
Note shall designate to Maker in writing.

3. Maker may prepay this Note in whole or in part at any time without premium or
penalty.

4. This Note is the note referred to in, and is entitled to the benefits of, and
is secured as provided in, the Pledge Agreement. Reference is hereby made to the
Pledge Agreement for a description of the properties and assets in which a
security interest has been granted, the nature and extent of the security, and
the rights of the holder of this Note in respect thereof.

5. Upon the occurrence of any of the following events, all amounts payable
hereunder shall, without notice or demand, become due and payable at such times
as are indicated below, and the holder shall thereupon have all rights and
remedies provided hereunder, in any other agreement between Payee and Maker or
otherwise available at law or in equity:

                  (a) In the event Maker's employment with Payee terminates for
         any reason (other than by reason of death or disability) prior to the
         Maturity Date, the outstanding principal balance hereof, together with
         all accrued interest hereon, shall become due and payable not later
         than 90 days following the date of termination; provided that such
         acceleration shall not occur under this paragraph if such termination
         of employment occurs after a "Change in Control" (as that term is
         defined in the Payee's 1997 Stock Option Plan, as amended) of the Payee
         and so long as the Payee's common stock (or successor security) is not
         publicly traded.

                  (b) In the event of any sale of the Pledged Collateral (as
         defined in the Pledge Agreement) (other than a transfer of any Estate
         Planning Shares (as defined in the Pledge
<PAGE>
         Agreement)), the principal amount of this Note shall become due and
         payable in the same proportion of the total original principal amount
         as the proportion of the total Pledged Collateral that are sold.

                  (c) In the event of any exchange of the Pledged Collateral in
         a sale or merger of the Payee for cash or securities that are publicly
         traded and freely marketable by the Maker.

                  (d) In the event of an initial public offering of equity
         securities of Payee which is registered under the Securities Act of
         1933, as amended, the outstanding principal balance hereof, together
         with all accrued interest hereon, shall become due and payable no later
         than one year following the initial public offering.

6. No failure or delay on the part of the holder to insist on strict performance
of Maker's obligations hereunder or to exercise any remedy shall constitute a
waiver of the holder's rights in that or any other instance. No waiver of any of
the holder's rights shall be effective unless in writing, and any waiver of any
default or any instance of non-compliance shall be limited to its express terms
and shall not extend to any other default or instance of non-compliance.

7. Maker and each endorser hereby waives presentment, notice of nonpayment or
dishonor, protest, notice of protest and all other notices in connection with
the delivery, acceptance, performance, default or enforcement of payment of this
Note, and hereby waives all notice or right of approval of any extensions,
renewals, modifications or forbearances which may be allowed.

8. Any proceeding relating to this Note may be instituted in any federal court
in the Eastern District of Pennsylvania or any state court located in Chester
County in the Commonwealth of Pennsylvania and Maker irrevocably submits to the
nonexclusive jurisdiction of any such court and waives any objection Maker may
have to the conduct of any proceeding in any such court based on improper venue
or forum non conveniens. Because of the greater time and expense required
therefor, Maker hereby waives, to the extent permitted by law, a trial by jury.

9. Maker shall pay all reasonable costs and expenses (including attorneys' fees)
incurred by the holder relating to the enforcement of this Note.

10. Any provision hereof found to be illegal, invalid or unenforceable for any
reason whatsoever shall not affect the validity, legality or enforceability of
the remainder hereof.

11. If the effective interest rate on this Note would otherwise violate any
applicable usury law, then the interest rate shall be reduced to the maximum
permissible rate and any payment received by the holder in excess of the maximum
permissible rate shall be treated as a prepayment of the principal of this Note.

12. This Note shall be binding upon Maker's heirs, personal representatives and
assigns and shall inure to the benefit of each holder of this Note and such
holder's heirs, personal representatives, successors, endorsees and assigns.

                                     - 2 -
<PAGE>
13. This Note has been delivered in the Commonwealth of Pennsylvania and shall
be governed by the laws of that Commonwealth.

         IN WITNESS WHEREOF, the undersigned, intending to be legally bound,
have duly executed and delivered this instrument.

                                            /s/  Gregory Bentley
                                          --------------------------------------
                                          Gregory Bentley

                                            /s/  Caroline Bentley
                                          --------------------------------------
                                          Caroline Bentley

                                     - 3 -

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00038-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00038-of-00352.parquet"}]]