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                                                                   EXHIBIT 10.13

                                 PROMISSORY NOTE

                                                            SAN JOSE, CALIFORNIA

NOT TO EXCEED $1,000,000.00                               OCTOBER 27, 2003

         FOR VALUE RECEIVED, the undersigned, BACKWEB TECHNOLOGIES INC., A
DELAWARE CORPORATION ("Maker"), unconditionally promises to pay to CA-GATEWAY
OFFICE LIMITED PARTNERSHIP, A DELAWARE LIMITED PARTNERSHIP ("Payee", which term
shall mean the holder, from time to time, of this Note), a principal sum
determined in accordance with the terms hereof but not to exceed ONE MILLION
DOLLARS ($1,000,000.00). Maker shall pay the then current outstanding principal
amount (as determined in accordance with Section 10 of this Note) to Payee on or
before any date due as provided herein (each a "Maturity Date"). Each such
payment shall be made by good and lawful check or money order payable to EQUITY
OFFICE PROPERTIES, and shall be delivered on or before the close of business to
CA-GATEWAY OFFICE LIMITED PARTNERSHIP, P.O. Box 45587, Dept. 13472, San
Francisco, CA 94145-0587, or such other party or place as Payee may designate by
written notice to Maker. None of the sums due hereunder shall be subject to any
claim or offset of any kind or nature whatsoever. The principal owing under this
Note that is not paid when due shall bear interest ("Default Interest") at the
lesser of 18% per annum or the highest rate permitted by law. All Default
Interest shall be computed on the basis of a 360-day year composed of twelve
30-day months. Payee may transfer this Note, in part or in whole to any party
designated by Payee by written notice to Maker.

1.       PERMISSIBLE PREPAYMENTS. The principal amount of this Note may at any
         time and from time to time be prepaid in whole or in part, together
         with interest accrued thereon to the date of such prepayment, without
         premium or penalty, at the place of payment designated above. Partial
         prepayments shall not delay any Maturity Date.

2.       DEFAULT. At the option of Payee, the then-current outstanding but
         unpaid principal amount balance of this Note (as determined in
         accordance with Section 10 of this Note), including all accrued but
         unpaid interest and accrued but unpaid Default Interest, shall become
         immediately due and payable, without notice or demand, upon the
         occurrence at any time of any of the following:

         a.       failure to pay any amounts due pursuant to the terms hereof
                  when due; or

         b.       failure to pay the outstanding balance due hereunder, together
                  with accrued but unpaid interest and accrued but unpaid
                  Default Interest, if any, thereon, upon any Maturity Date,
                  whether by acceleration or otherwise; or

         c.       Maker shall become insolvent, or shall make a transfer in
                  fraud of creditors, or shall commit an act of bankruptcy or
                  shall make an assignment for the benefit of creditors, or
                  Maker shall admit in writing its inability to pay its debts as
                  they become due; or

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         d.       Maker shall file a petition under any section or chapter of
                  the United States Bankruptcy Code, as amended, pertaining to
                  bankruptcy, or under any similar law or statute of the United
                  States or any State thereof, or Maker shall be adjudged
                  bankrupt or insolvent in proceedings filed against Maker; or a
                  petition or answer proposing the adjudication of Maker as a
                  debtor or its reorganization under any present or future
                  federal or state bankruptcy or similar law shall be filed in
                  any court and such petition or answer shall not be discharged
                  or denied within 60 days after the filing thereof; or

         e.       a receiver or trustee shall be appointed for all or
                  substantially all of the assets of Maker in any proceeding
                  brought by or against Maker and shall not be discharged within
                  60 days after such appointment; or

         f.       failure to pay when due any payment of Rent or other amounts
                  due under certain office lease dated December 23, 1998 (the
                  "Original Lease") by and between Maker and Payee, which
                  Original Lease has been previously amended by that certain 1st
                  Amendment to Lease - Expansion dated as of May 12, 2000 (the
                  "First Amendment") and by that certain 2nd Amendment to Lease
                  - Expansion dated as of November 7, 2000 (the "Second
                  Amendment"), and by that certain Third Amendment of even date
                  herewith (the "Third Amendment", and together with the
                  Original Lease, the First Amendment and the Second Amendment,
                  collectively, the "Lease") for approximately 17,569 rentable
                  square feet in the building commonly known as Gateway Office
                  IIB located at 2077 Gateway Place, San Jose, California; or

         g.       Intentionally omitted.

         The remedies of Payee as provided herein, or at law or in equity, shall
         be cumulative and concurrent, and may be pursued singly, successively,
         or together at the sole discretion of Payee, and may be exercised as
         often as occasion therefor shall occur. The failure at any time to
         exercise any right or remedy shall not constitute a waiver of the right
         to exercise the right or remedy at any other time.

3.       ENFORCEMENT COSTS. If this Note is placed in the hands of an attorney
         for collection or is collected through any legal proceeding, or if
         Payee incurs any costs or expenses in enforcing its rights hereunder,
         the Maker promises to pay expenses, court costs and reasonable
         attorneys' fees, incurred in connection with such matter, and in
         addition to all such costs and expenses, interest thereon from the date
         of such demand until paid at the Default Interest rate.

4.       WAIVER. Presentment, demand, protest, notices of protest, dishonor and
         non-payment of this Note and all notices of every kind are hereby
         waived by Maker. To the extent permitted by applicable law, the defense
         of the statute of limitations is hereby waived by Maker. The Maker
         agrees that the time of payment of

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         principal or interest on this Note may be extended, without in any way
         altering, releasing, affecting or limiting the liability of Maker
         hereunder. Maker acknowledges that the provisions of California Civil
         Code Section 2924(i) are not applicable to this Note and expressly
         waives any rights thereunder.

5.       NOTICES. Any notice desired to be given to any other party hereunder
         shall be in writing and delivered by hand or sent by registered or
         certified mail with return receipt requested, or sent by overnight or
         same day commercial courier service at the party's respective notice
         address(es) below. Each notice shall be deemed to have been received or
         given on the earlier to occur of (i) actual delivery or the date on
         which delivery is refused, if delivered by hand delivery, (ii) three
         (3) days after notice is deposited in the U.S. mail, if delivered via
         certified mail, or (iii) one (1) business day after deposit with a
         commercial courier service. Either party may, at any time, change its
         notice address (other than to a P.O. Box) by giving the other party at
         least 10 days advance written notice of the new address in the manner
         described in this Section.

         Payee's address for notices is:

         CA-GATEWAY OFFICE LIMITED PARTNERSHIP
         c/o Equity Office Properties
         1740 Technology Drive, Suite 150
         San Jose, CA 95110
         Attention:  Building Manager

         With a copy to:

         Equity Office Properties Trust
         Two North Riverside Plaza
         Suite 2100
         Chicago, Illinois 60606
         Attention: Regional Counsel - San Jose Region

         Maker's address for notices is:

         Backweb Technologies Inc.
         2077 Gateway Place
         Suite 500
         San Jose, California 95110
         Attention: Finance Department

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6.       GUARANTY. As security for the payment of the monies owing under this
         Note, Maker has delivered or has caused to be delivered to Payee a
         Guaranty (the "Guaranty") entered into by Guarantor (as defined in
         Section 10.a below) for the benefit of Payee, which Guaranty secures
         Maker's performance hereunder.

7.       TRIAL BY JURY WAIVER. TO THE EXTENT PERMITTED BY LAW, EACH OF MAKER AND
         PAYEE HEREBY EXPRESSLY WAIVES ANY RIGHT TO TRIAL BY JURY OF ANY ACTION,
         CAUSE OF ACTION, CLAIM, DEMAND OR PROCEEDING ARISING UNDER OR WITH
         RESPECT TO THIS NOTE, OR IN ANY WAY CONNECTED WITH, RELATED TO, OR
         INCIDENTAL TO THE DEALINGS OF MAKER AND PAYEE WITH RESPECT TO THIS NOTE
         OR THE TRANSACTIONS RELATED HERETO, IN EACH CASE, WHETHER NOW EXISTING
         OR HEREAFTER ARISING, AND WHETHER SOUNDING IN CONTRACT, TORT, OR
         OTHERWISE. TO THE MAXIMUM EXTENT PERMITTED BY LAW, EACH OF MAKER AND
         PAYEE HEREBY AGREES THAT ANY SUCH ACTION, CAUSE OF ACTION, CLAIM,
         DEMAND, OR PROCEEDING SHALL BE DECIDED BY A COURT TRIAL WITHOUT A JURY
         AND THAT EITHER PARTY MAY FILE AN ORIGINAL COUNTERPART OF THIS SECTION
         WITH ANY COURT OR OTHER TRIBUNAL AS WRITTEN EVIDENCE OF THE CONSENT OF
         MAKER TO THE WAIVER OF ITS RIGHT TO TRIAL BY JURY.

8.       MISCELLANEOUS.

         a.       No single or partial exercise of any power hereunder or under
                  the Lease or any other agreement pertaining to the principal
                  and interest due hereunder and/or any Base Rent or Additional
                  Rent or Cash Consideration due under the Lease shall preclude
                  other or further exercise thereof or the exercise of any other
                  power or right. No delay or omission on the part of the Payee
                  in exercising any right hereunder shall operate as a waiver of
                  such right or of any other right under this Note. All remedies
                  of Payee shall be cumulative and concurrent, and may be
                  pursued singularly, successively or concurrent, at the option
                  of Payee.

         b.       Time is of the essence with respect to the performance of the
                  obligations of Maker under this Note.

         c.       The undersigned, if there be more than one, shall be jointly
                  and severally liable hereunder, and for purposes of such
                  several liability the word "undersigned" or "Maker" wherever
                  used herein shall be construed to refer to each of the
                  undersigned parties separately, all in the same manner and
                  with the same effect as if each of them had signed separate
                  instruments, and this Note shall not be revoked or impaired as
                  to any of such parties by the death of another party or by
                  revocation or release of any obligations hereunder of any
                  other party. The term "Maker" shall also include the heirs,
                  successors and assigns of the original named Maker hereunder.

         d.       This Note shall be governed by and construed in accordance
                  with the internal laws of the state where this Note was
                  executed and delivered. For

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                  the purpose solely of litigating any dispute under this Note,
                  the Maker submits to the jurisdiction of the courts of said
                  state. The parties acknowledge and agree this Note was
                  executed and delivered in the State of California.

         e.       Any provision of this Note which is unenforceable, invalid or
                  contrary to law, or the inclusion of which would affect the
                  validity, legality or enforcement of this Note, shall be of no
                  effect, and in such case, all the remaining terms and
                  provisions of this Note shall subsist and be fully effective
                  according to the terms of this Note the same as though any
                  such unenforceable, invalid or contrary provision had never
                  been included herein.

         f.       All payments received on account of the indebtedness evidenced
                  by this Note shall be applied to principal, interest, Default
                  Interest and any costs and expenses owing to Payee as a result
                  of this Note, in whatever order, combination and amounts as
                  Payee, in its sole and absolute discretion, decides.

         g.       This Note, and the terms and provisions hereof, shall be
                  binding upon the Maker and each Maker's heirs, executors,
                  personal representatives, successors, administrators, and
                  assigns, and shall inure to the benefit of any holder hereof.
                  Payee has the right to sell, assign, pledge, hypothecate or
                  negotiate this Note, and all Payee's rights hereunder, to any
                  person or entity without notice to or consent of any Maker.

         h.       All amounts due hereunder shall be paid without deduction, set
                  off or counterclaim, Maker expressly waiving any such rights
                  to deduction, set off or counterclaim.

         i.       Each signatory of this Note represents hereby that he or she
                  has the authority to execute and deliver the same on behalf of
                  the party hereto for which such signatory is acting.

         j.       Upon receipt by Maker of written notice from Payee of the
                  loss, theft, destruction or mutilation of this Note, Maker
                  will execute and deliver to Payee, in lieu thereof, a
                  replacement note in identical form to this Note and dated as
                  of the date of this Note. Upon delivery to Payee of such
                  replacement note, all references in the Security Documents to
                  this Note shall be deemed to be references to such replacement
                  note.

         k.       ALL AGREEMENTS BETWEEN MAKER AND PAYEE, WHETHER NOW EXISTING
                  OR HEREAFTER ARISING, AND WHETHER WRITTEN OR ORAL, ARE HEREBY
                  EXPRESSLY LIMITED SO THAT IN NO CONTINGENCY OR EVENT
                  WHATSOEVER, WHETHER BY REASON OF ACCELERATION OF THE MATURITY
                  OF THIS NOTE OR OTHERWISE, SHALL THE AMOUNT PAID OR AGREED TO
                  BE

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                  PAID TO PAYEE OR THE HOLDER OF THIS NOTE FOR THE USE,
                  FORBEARANCE OR DETENTION OF THE MONEY LOANED PURSUANT HERETO
                  OR OTHERWISE, OR FOR THE PAYMENT OR PERFORMANCE OF ANY
                  COVENANT OR OBLIGATION CONTAINED HEREIN OR IN ANY OTHER
                  DOCUMENT EXECUTED IN CONNECTION HEREWITH, EXCEED THE MAXIMUM
                  AMOUNT PERMISSIBLE UNDER APPLICABLE LAW. IF, FROM ANY
                  CIRCUMSTANCE OR CONTINGENCY WHATSOEVER, FULFILLMENT OF ANY
                  PROVISION HEREOF OR OF ANY OTHER DOCUMENT EXECUTED IN
                  CONNECTION HEREWITH, AT THE TIME PERFORMANCE OF SUCH PROVISION
                  SHALL BE DUE, SHALL INVOLVE TRANSCENDING THE LIMIT OF VALIDITY
                  PRESCRIBED BY LAW, THEN, IPSO FACTO, THE OBLIGATION TO BE
                  FULFILLED SHALL BE REDUCED TO THE LIMIT OF SUCH VALIDITY, AND
                  IF FROM ANY SUCH CIRCUMSTANCE OR CONTINGENCY PAYEE SHALL EVER
                  RECEIVE AS INTEREST OR OTHERWISE AN AMOUNT WHICH WOULD EXCEED
                  THE MAXIMUM RATE OF INTEREST PERMITTED BY APPLICABLE LAW, THE
                  AMOUNT OF SUCH EXCESS SHALL BE APPLIED TO A REDUCTION OF THE
                  INDEBTEDNESS EVIDENCED BY THIS NOTE, AND NOT TO THE PAYMENT OF
                  INTEREST, AND IF SUCH EXCESSIVE INTEREST EXCEEDS SUCH
                  INDEBTEDNESS, THE AMOUNT OF SUCH EXCESSIVE INTEREST SHALL BE
                  REFUNDED TO MAKER. IF AT ANY TIME THIS NOTE PRESCRIBES A RATE
                  OF INTEREST IN EXCESS OF THE MAXIMUM RATE PERMITTED BY LAW,
                  ALL SUMS PAID OR AGREED TO BE PAID TO PAYEE FOR THE USE,
                  FORBEARANCE OR DETENTION OF THE MONEY LOANED PURSUANT TO THIS
                  NOTE SHALL BE AMORTIZED, PRORATED, ALLOCATED AND SPREAD
                  THROUGHOUT THE FULL TERM OF SUCH INDEBTEDNESS UNTIL PAYMENT IN
                  FULL, SO THAT THE ACTUAL RATE OF INTEREST ON ACCOUNT OF SUCH
                  INDEBTEDNESS IS UNIFORM THROUGHOUT THE TERM HEREOF. ANY
                  PREPAYMENT OF THE OUTSTANDING PRINCIPAL BALANCE OF THE LOAN
                  MADE PURSUANT TO THE FOREGOING PROVISIONS SHALL BE WITHOUT ANY
                  PREPAYMENT PENALTY OR PREMIUM.

9.       MAKER'S REPRESENTATIONS AND WARRANTIES. Maker hereby represents and
         warrants to Payee as follows:

         a.       Maker is duly formed, validly existing and in good standing
                  under the laws of the State of Delaware.

         b.       Maker has the power and authority to enter into this Note.
                  Maker's representatives are duly authorized to execute and
                  deliver this Note on behalf of Maker and to generally perform
                  Maker's obligations hereunder.

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                  This Note does not violate any provision of any agreement or
                  judicial order to which Maker is a party or to which maker is
                  subject.

         c.       Maker has not (i) made a general assignment for the benefit of
                  creditors, (ii) filed any voluntary petition in bankruptcy or
                  suffered the filing of any involuntary petition by Maker's
                  creditors, (iii) suffered the appointment of a receiver to
                  take possession of all, or substantially all, of Maker's
                  assets, (iv) suffered the attachment or other judicial seizure
                  of all, or substantially all, of Maker's assets, (v) admitted
                  in writing its inability to pay its debts as they come due, or
                  (vi) made an offer of settlement, extension or composition to
                  its creditors generally.

10.      DETERMINATION OF PRINCIPAL AMOUNT. The Principal Amount of this Note
         shall equal the total Additional Reduction Fee (as defined below).
         Maker shall pay to Payee, by cashier's or certified check or by wire
         transfer of immediately available funds to an account designated by
         Payee an additional reduction fee (the "Additional Reduction Fee) in
         the amount and on the dates as hereby provided:

         a.       Any sums invested from any source whatsoever (either debt or
                  equity) in Maker and/or BackWeb Technologies Ltd., an Israeli
                  corporation ("Guarantor"), in the aggregate (the "Investment
                  Dollars") commencing on October 1, 2002 through and including
                  June 30, 2005 (the "Investment Period") shall be subject to
                  the following payment schedule: Within 3 business days
                  following receipt, Maker shall pay to Payee (i) 5% of any of
                  any Investment Dollars equal to or in excess of $1.00 through
                  and including $2,000,000.00, (ii) 7% of any Investment Dollars
                  in excess of $2,000,000.00 though and including $5,000,000.00,
                  and (iii) 10% of any Investment Dollars in excess of
                  $5,000,000.00. Investment Dollars shall expressly exclude
                  funds received on the exercise of stock options or as part of
                  Tenant's or Guarantor's (as the case may be) Employee Stock
                  Purchase Plan. Further, Investment Dollars shall also exclude
                  funds received in connection with Tenant's or Guarantor's line
                  of credit or factoring activities to the extent Payee
                  reasonably determines that any such amounts constitute debt to
                  Tenant and/or Guarantor, as the case may be.

         b.       Additionally, and notwithstanding the foregoing, if at any
                  time prior to the expiration of the Investment Period, Maker's
                  and/or Guarantor's revenues (as determined in accordance with
                  generally accepted accounting principles and in accordance
                  with the terms of this Note) in any calendar year equal or
                  exceed $20,000,000.00 in total, Maker shall, on or before the
                  earlier of (i) February 15th of the following calendar year or
                  (ii) thirty (30) days following the expiration of the calendar
                  quarter in which Maker's and/or Guarantor's revenues (as
                  determined in accordance with generally accepted accounting
                  principles and in accordance with the terms of this Note)
                  equal or exceed $20,000,000.00 in total, deliver to Payee as
                  part of

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                  the Additional Reduction Fee an amount equal to $1,000,000.00
                  less the amount of any sums paid by Maker to Payee in
                  connection with any Investment Dollars as such payment is
                  described the preceding paragraph (the "Cash Portion of the
                  Additional Reduction Fee"). In no event shall the total
                  Additional Reduction Fee received by Payee exceed
                  $1,000,000.00.

         c.       Maker shall, at the same time that it publicly announces its
                  financial results following the end of each quarter (but in no
                  event more than within forty-five (45) days following the end
                  of each calendar quarter), provide to Payee a written
                  statement prepared by either of an executive officer of Maker,
                  Maker's Vice President of Finance or Maker's certified public
                  accounting firm certifying as true, complete and correct in
                  all material aspects: (a)(x) Maker and/or Guarantor has
                  received no Investment Dollars the previous calendar quarter,
                  or (y) the amount of and other material details regarding the
                  total amount of any Investment Dollars received by Maker
                  and/or Guarantor the previous calendar quarter, and (b) the
                  amount of each of Maker's and Guarantor's revenues for the
                  previous calendar quarter determined in accordance with
                  generally accepted accounting principles. Payee shall have the
                  right to transfer and assign, in whole or in part, all of its
                  rights in and to it's portion of the Investment Dollars and/or
                  the Cash Portion of the Additional Reduction Fee by providing
                  notice to Maker of such transfer at any time (subject to
                  compliance with applicable law). Unless otherwise indicated in
                  writing by Payee, payments of the Additional Reduction Fee
                  shall be delivered by Maker to Payee in accordance with the
                  terms and conditions contained herein. Payee may give Maker
                  written notice ("Review Notice") that Payee intends to review
                  Maker's and/or Guarantor's records with respect to the
                  foregoing. Within a reasonable time after receipt of the
                  Review Notice, Maker shall make all pertinent records
                  available for inspection (at the building in which the
                  premises under the Lease is located) that are reasonably
                  necessary for Payee to conduct its review.

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         This Note is entered into by Maker upon the date first written above.

                                       MAKER:

                                       BACKWEB TECHNOLOGIES INC., A
                                       DELAWARE CORPORATION

                                       By: /S/ MICHAEL A. MORGAN
                                           ----------------------

                                       Name: Michael A. Morgan

                                       Title:  CFO