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                                                                   Exhibit 10.13

                                     [LOGO]
                               Silicon Valley Bank
                            3003 Tasman Drive/HF 170
                              Santa Clara, CA 95054
                       (408) 654-1000 - Fax (408) 980-6410


      This NON-RECOURSE RECEIVABLES PURCHASE AGREEMENT (the "Agreement"), dated
as of September 27, 2000, is between Silicon Valley Bank, ("Buyer") and ART
TECHNOLOGY GROUP, INC. a Delaware corporation, ("Seller"), with its chief
executive office at:

            Street Address:      25 First Street
            City:                Cambridge
            County:
            State:               Massachusetts
            Zip code:            02144
            Fax:                 (617)386-1111

      1. Definitions. In this Agreement:

            1.1 "Payment" is when Buyer has received payments equal to the Total
Purchased Receivables.

            1.2 "Purchased Receivables" is all accounts, receivables, chattel
paper, instruments, contract rights, documents, general intangibles, letters of
credit, drafts, bankers acceptances other rights to payment and all proceeds
arising from the invoices and other agreements on the Schedule.

            1.3 "Related Property" is all returned or rejected goods connected
with the Purchased Receivables or books and records about the Purchased
Receivables or returned or rejected goods; or proceeds from voluntary or
involuntary dispositions, including insurance proceeds.

            1.3 "Schedule" is the attached schedule showing the: Purchase Date,
Due Date, Total Purchased Receivables, Discount Rate, Purchase Price and
Administrative Fee amount.

      2. Purchase and Sale of Receivables.

            2.1 Sale and Purchase. On the Purchase Date, Seller sells and Buyer
buys Seller's right, title, and interest (but none of Sellers obligations) to
payment from any person liable on a Purchased Receivable, ("Account Debtors").

      Each purchase and sale is at Buyer's and Seller's discretion. Buyer will
not (i) pay Seller an aggregate outstanding amount exceeding Ten Million Dollars
($10,000,000.00) or (ii) buy any Purchased Receivable after September 27, 2001
(the "Maturity Date"). Each purchase and sale will be on an assignment form
acceptable to Buyer.

            2.2 Payment of Purchase Price and Late Payment.

                  (a) Payment of Purchase Price. For each Purchased Receivable,
Buyer will pay Seller, on the Purchase Date, the Purchase Price, less the
Administrative Fee and legal fees (if any).


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                  (b) Late Payment. If Payment is made after the Due Date, as
listed on the Schedule, then on the earlier of Payment or 90 days, Seller will
also pay Buyer the product of the Discount Rate and the average daily balance of
the unpaid Purchased Receivable multiplied by the number of days between the
scheduled payment date or the earlier of the date of actual payment or 90 days
after the scheduled payment date, divided by 360.

            2.3 Seller may not sell or convey any interest in Related Property
without Buyer's prior written consent. Seller will sign UCC financing statements
and any other instruments or documents to evidence, perfect or protect Buyer's
interests in the Purchased Receivables and Related Property. Seller will deliver
to Buyer all original instruments, chattel paper and documents about Purchased
Receivables and Related Property.

      3. Collections, Payments and Remittances.

            3.1 Application of Payments. All payments for any Purchased
Receivable, received by Seller or Buyer, are Buyer's property.

            3.2 Collection by Seller.

                  (a) Buyer appoints Seller its attorney-in-fact to receive
payments and enforce its rights and designates Seller it's assignee for
collection. Seller will use diligence and commercially reasonable means to
collect Purchased Receivables. Buyer may revoke these appointments at any time.

                  (b) Seller will begin legal proceedings about Purchased
Receivables in its name (as Buyer's assignee for collection or enforcement) or,
with Buyer's prior written consent, in Buyer's name. Seller will not make Buyer
party to any litigation or arbitration without Buyer's written consent.

                  (c) Seller will hold in trust for and give Buyer: (i) all
payments made by Account Debtors, and (ii) all instruments, chattel paper and
other proceeds of the Purchased Receivables.

                  (d) Unless an Event of Repurchase occurs and continues Seller
will remit payments to Buyer on the last business day of each week ("Settlement
Date") starting the week after the Purchase Date. On each Settlement Date Seller
will deliver a report acceptable to Buyer of account activity (including dates
and amounts of payments) and changes for each Purchased Receivable.

            3.3 No Obligation to Take Action. Buyer has a right, but no
obligation, to perform Seller's obligations or to take action on any Purchased
Receivable (including on defaulted Purchased Receivables).

      4. Non-Recourse; Repurchase Obligations.

            4.1 Non-Recourse and Seller's Agreement to Repurchase. Buyer
acquires Purchased Receivables without recourse, except Seller will, at Buyer's
option, repurchase from Buyer any Purchased Receivable for a purchase price
equal to the unpaid portion of any Purchased Receivable:

                  (a) For which there has been any breach of warranty,
representation or covenant in this Agreement; or

                  (b) For which the Account Debtor asserts any discount,
allowance, return, dispute, defense, right of recoupment, right of return,
warranty claim, or short payment.

Seller will reimburse Buyer for Buyer's reasonable attorneys' and professional
fees and expenses and all court costs for collecting Purchased Receivables
and/or enforcing its rights under this Agreement.


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            4.2 Payment to Buyer. Seller will pay Buyer in immediately available
funds.

      5. Representations, Warranties and Covenants.

            5.1 Purchased Receivables - Warranties, Representations and
Covenants. Seller represents, warrants and covenants for each Purchased
Receivable:

                  (a) It is the owner with legal right to sell, transfer and
assign it;

                  (b) The correct amount is on the Schedule and is not disputed;

                  (c) No payment is contingent on any obligation or contract,
and it has fulfilled all its obligations as of the Purchase Date;

                  (d) It is based on actual sale and delivery of goods and/or
services rendered, due no later than its Due Date and owing to Seller, it is not
past due or in default, has not been previously sold, assigned, transferred, or
pledged, and is free of any liens, security interests and encumbrances;

                  (e) There are no defenses, offsets, counterclaims or
agreements in which the Account Debtor may claim any deduction or discount;

                  (f) It reasonably believes no Account Debtor is insolvent as
defined in the United States Bankruptcy Code ("US Code") or the California
Uniform Commercial Code ("UCC") and no Account Debtor has filed or had filed
against it a voluntary or involuntary petition for relief under the US Code.;
and

                  (g) No Account Debtor has objected to payment for or the
quality or quantity of the subject of the Purchased Receivable.

            5.2 Additional Warranties. Representations and Covenants. Seller
represents, warrants and covenants:

                  (a) Its name, form of organization, chief executive office,
and the place where the records about all Purchased Receivables are kept is
shown at the beginning of this Agreement and it will give Buyer at least 10 days
prior written notice of changes to its name, organization, chief executive
office or location of records.

                  (b) It has not filed a voluntary petition or had filed against
it an involuntary petition under the US Code and does not anticipate any filing;

                  (c) If Payment of any Purchased Receivable does not occur by
its Due Date then Seller will provide a written report, within 10 days, of the
reasons for the delay.

                  (d) While any Purchased Receivable is outstanding, Seller will
give Buyer copies of all Forms 10-K, 1 0-Q and 8-K (or equivalents) within 5
days of its filing with the Securities and Exchange Commission.

      6. Adjustments. If any Account Debtor asserts a discount, allowance,
return, offset, defense, warranty claim, or the like (an "Adjustment") Seller
will promptly advise Buyer and, with Buyer's approval, resolve the dispute.
Seller will resell any rejected, returned, or recovered personal property for
Buyer, at Seller's expense, with the proceeds payable to Buyer. While Seller has
returned goods that are Buyer's property, Seller will segregate and mark them
"property of Silicon Valley Bank." Buyer owns the Purchased Receivables and
until Payment has the right to take possession of any rejected, returned, or
recovered personal property.


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      7. Indemnification.

                  (a) If any Account Debtor is released from any payment
obligation for any Purchased Receivable because of: (i) Seller's act or
omission; or (ii) any of the documentation about the Purchased Receivables which
results in termination of any part of the Account Debtor's obligation for the
Purchased Receivables, then Seller will pay Buyer the lesser of the amount of
the Purchased Receivable not payable or the unpaid portion of the Purchased
Receivable.

                  (b) Seller indemnifies and holds Buyer harmless from any taxes
from this transaction (except Buyer's income taxes) and costs, expenses and
reasonable attorney fees if Buyer promptly notifies it of any taxes of which
Buyer has notice.

      8. Repurchase Events. Any of the following is an Event of Repurchase:

                  (a) Seller fails to pay Buyer any amount when due under
Section 2.2(b), 3.2(c), 3.2(d), 4.1, 7 or 10;

                  (b) An involuntary lien, garnishment, attachment or the like
is issued against or attaches to the Purchased Receivables or Related Property;
and

                  (c) Seller breaches a covenant, agreement, warranty, or
representation in this Agreement and the breach is not cured to Buyer's
satisfaction within 10 days after Buyer gives Seller oral or written notice. A
breach that cannot be cured is an immediate default.

      9. Repurchase Option. When an Event of Repurchase occurs Buyer shall have
a right to require Seller to repurchase all of the affected Purchased
Receivables for a purchase price equal to the amount(s) specified in Section
4.1. Buyer shall also have all rights and remedies under this Agreement and the
law, including those of a secured party under the UCC, and the right to collect,
dispose of, sell, lease or use all Purchased Receivables and Related Property.

      10. Fees, Costs and Expenses. Immediately on demand Seller will pay all
reasonable fees, costs and expenses (including attorney and professional fees)
that Buyer incurs from (a) preparing, negotiating, administering and enforcing
this Agreement or any other agreement, including amendments, waivers or
consents, (b) litigation or disputes relating to the Purchased Receivables, the
Related Property, this Agreement or any other agreement, (c) enforcing rights
against Seller, (d) protecting or enforcing its title to the Purchased
Receivables or its security interest in the Related Property, (e) collecting any
amounts due from Seller or for a Purchased Receivable under a breach of Seller's
representation, warranty or covenant and (f) any bankruptcy case or insolvency
proceeding involving Seller.

      11. Choice of Law, Venue and Jury Trial Waiver. California law governs
this Agreement. Seller and Buyer each submit to the exclusive jurisdiction of
the State and Federal courts in Santa Clara County, California.

SELLER AND BUYER EACH WAIVE ITS RIGHT TO A JURY TRIAL FROM ANY CAUSE OF ACTION
RELATED TO AGREEMENT, INCLUDING CONTRACT, TORT, BREACH OF DUTY OR OTHER CLAIM.
THIS WAIVER IS A MATERIAL INDUCEMENT FOR BOTH PARTIES TO ENTER THIS AGREEMENT.
EACH PARTY HAS REVIEWED THIS WAIVER WITH ITS COUNSEL.
      12. Notices. Notices or demands by either party about this Agreement must
be in writing and personally delivered or sent by an overnight delivery service,
by certified mail postage prepaid return receipt requested, or by FAX to the
addresses below:

      Seller: ART TECHNOLOGY GROUP, INC. 25 First Street


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              Cambridge, MA 02144
              Attn: Chief Financial Officer
              FAX: (617) 386-1111

      Buyer:  Silicon Valley Bank
              3003 Tasman Drive/HF 170
              Santa Clara, CA 95054
              Attn: Credit Manager
              FAX: (408)980-6410

      A party may change notice address by written notice to the other party.

      13. General Provisions.

            13.1 Successors and Assigns. This Agreement binds and is for the
benefit of successors and permitted assigns of each party. Seller may not assign
this Agreement or any rights under it without Buyer's prior written consent
which may be granted or withheld in Buyer's discretion. Buyer may, without the
consent of or notice to Seller, sell, transfer, or grant participation in any
part of Buyer's obligations, rights or benefits under this Agreement.

            13.2 Indemnification. Seller will indemnify, defend and hold
harmless Buyer and its officers, employees, and agents against: (a) obligations,
demands, claims, and liabilities asserted by any other party in connection with
the transactions contemplated by this Agreement; and (b) losses or expenses
incurred, or paid by Seller from or consequential to transactions between Buyer
and Seller (including reasonable attorneys fees and expenses), except for losses
caused by Buyer's gross negligence or willful misconduct.

            13.3 Time of Essence. Time is of the essence for performance of all
obligations in this Agreement.

            13.4 Severability of Provision. Each provision of this Agreement is
severable from every other provision in determining the enforceability of any
provision.

            13.5 Amendments in Writing, Integration. All amendments to this
Agreement must be in writing. This Agreement is the entire agreement about this
subject matter and supersedes prior negotiations or agreements.

            13.6 Counterparts. This Agreement may be executed in any number of
counterparts and by different parties on separate counterparts and when executed
and delivered are one Agreement.

            13.7 Survival. All covenants, representations and warranties made in
this Agreement continue in full force while any Purchased Receivable amount
remains outstanding. Seller's indemnification obligations survive until all
statutes of limitations for actions that may be brought against Buyer have run.

            13.8 Confidential Information. Buyer will use the same degree of
care in handling Seller's confidential information that it uses for its own
proprietary information, but may disclose information; (i) to its subsidiaries
or affiliates in connection with their business with Seller, (ii) to prospective
transferees or purchasers of any interest in the Agreement, (iii) as required by
law, regulation, subpoena, or other order, (iv) as required in connection with
an examination or audit and (v) as it considers appropriate exercising the
remedies under this Agreement. Confidential information does not include
information that is either: (a) in the public domain or in Buyer's possession
when disclosed, or becomes part of the public domain after disclosure to Buyer;
or (b) disclosed to Buyer by a third party, if Buyer does not know that the
third party is prohibited from disclosing the information.


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SELLER:     ART TECHNOLOGY GROUP, INC,
            a Delaware corporation


By /s/ Ann Brady
   ------------------------------
Title CFO
     ----------------------------


BUYER:      SILICON VALLEY BANK


By
   ------------------------------
Title
     ----------------------------


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                          CORPORATE RESOLUTION TO SELL


I, the Secretary or Assistant Secretary of ART TECHNOLOGY GROUP, INC. (the
"Seller"), certify that:

      The Seller is a Delaware corporation, and

      Attachments 1 and 2 are copies of Seller's Articles of Incorporation and
      Bylaws which are currently effective, and

      At a duly held meeting of Seller's directors at which a quorum was present
      (or by other authorized corporate action) the following resolutions were
      adopted:

            "Resolved that any 1 of the following officers of Seller, whose
            signatures are below:

            Name                        Title                  Signature

            Ann Brady                   CFO                    /s/ Ann Brady
            -----------------           -----------------      -----------------
            Jeet Singh                  CEO                    /s/ Jeet Singh
            -----------------           -----------------      -----------------

            -----------------           -----------------      -----------------

            -----------------           -----------------      -----------------

            acting for Seller are authorized to:

            Execute Purchase Agreement. To enter a Purchase Agreement with
            Silicon Valley Bank ("Buyer") on terms agreed by them and Buyer for
            the sale of certain of Seller's accounts receivable and to execute
            renewals, extensions, modifications, refinancings, consolidations or
            substitutions of any accounts receivable and to do other acts and
            things and execute and deliver other documents that they consider
            necessary to carry out the effect of these Resolutions.

            Further Acts. To designate other individuals as authorized to
            request that Buyer purchase additional accounts receivable under the
            Purchase Agreement.

            Further Resolved that:

            any acts authorized by these Resolutions but performed before their
            passage are ratified, and

            these Resolutions remain effective and Buyer may rely on them until
            it receives written notice of their revocation, but that notice will
            not affect any of Seller's agreements or commitments then
            effective."

I also certify that the officers or agents above are duly elected or appointed
by Seller and hold the positions opposite their names and that the their
signatures are true and that the Resolutions are effective and have not been
modified or revoked.


/s/ [ILLEGIBLE]
--------------------------------------------                     ---------------
(signature) Assistant Secretary or Secretary                     Date
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                        SCHEDULE DATED September 29, 2000
                                       TO
                   NON-RECOURSE RECEIVABLES PURCHASE AGREEMENT
                         DATED AS OF September 27, 2000

Seller:                  Art Technology Group, Inc.

Buyer                    Silicon Valley Bank

Purchase Date:           September 29, 2000

Due Date:                45 days from Purchase Date

Total Purchased
Receivables:             $9,733,972.00 (See list of Receivables total)

Discount Rate:           10.5%

Purchase Price           $9,606,213.62 (is 98.69% of the Total Purchased
                         Receivables which is the Straight Discount of the Total
                         Purchased Receivables discounted from the Due Date to
                         the Purchase Date at the Discount Rate.

Administrative Fee:      0.375%

Seller warrants and represents that (a) its warranties and representations in
the Agreement are true and correct as of the date of this Schedule and (b) no
Event of Repurchase has occurred under the Agreement.


Seller:                  Art Technology Group Inc.


By:                      /s/ Jeet Singh
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Print Name/Title:        Jeet Singh, CEO
                         -------------------------------


Buyer:                   SILICON VALLEY BANK


By:
                         -------------------------------

Print Name/Title:
                         -------------------------------