<PAGE>
                                                                   Exhibit 10.19

THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED, OR ANY STATE SECURITIES LAWS, AND MAY
NOT BE SOLD, PLEDGED, OR OTHERWISE TRANSFERRED WITHOUT AN EFFECTIVE REGISTRATION
THEREOF UNDER SUCH ACT AND LAWS OR PURSUANT TO RULE 144 AND EXEMPTIONS UNDER
APPLICABLE STATE SECURITIES LAWS, OR, SUBJECT TO SECTIONS 4.3 HEREOF, AN OPINION
OF COUNSEL REASONABLY SATISFACTORY TO THE CORPORATION AND ITS COUNSEL, THAT SUCH
REGISTRATION IS NOT REQUIRED.

                            WARRANT TO PURCHASE STOCK

Issuer:              Greenfield Online, Inc., a Delaware corporation
Number of Shares:    686,577, subject to adjustment
Class of Stock:      Class A Common Stock, $ 0.0001 par value per share
Exercise Price:      $0.29 per share, subject to adjustment
Issue Date:          August 9, 2001
Expiration Date:     As set forth below

      THIS WARRANT CERTIFIES THAT, for the agreed upon value of $1.00 and for
other good and valuable consideration, this Warrant is issued to SILICON VALLEY
BANK (together with its successors and permitted assigns, the "Holder") by
GREENFIELD ONLINE, INC., a Delaware corporation (the "Company").

      Subject to the terms and conditions hereinafter set forth, the Holder is
entitled upon surrender of this Warrant and the duly executed subscription form
annexed hereto as Appendix 1, at the office of the Company, 21 River Road,
Wilton, Connecticut 06897, or such other office as the Company shall notify the
Holder of in writing, to purchase from the Company Six Hundred Eighty-Six
Thousand Five Hundred Seventy-Seven (686,577) fully paid and non-assessable
shares (the "Shares") of the Company's Class A Common Stock, $0.0001 par value
per share (the "Class"), at a purchase price per Share of Twenty-Nine Cents
($0.29) (the "Exercise Price"). Until such time as this Warrant is exercised in
full or expires, the Exercise Price and the number Shares are subject to
adjustment from time to time as hereinafter provided. This Warrant may be
exercised in whole or in part at any time and from time to time until 5:00 PM,
Eastern time July 9, 2006 (the "Expiration Date").

ARTICLE 1. EXERCISE.

            1.1 Method of Exercise. Holder may exercise this Warrant by
delivering a duly executed Notice of Exercise in substantially the form attached
as Appendix 1 to the principal office of the Company. Unless Holder is
exercising the conversion right set forth in Section 1.2, Holder shall also
deliver to the Company a check or wire transfer for immediately available funds,
for the aggregate Exercise Price for the Shares being purchased.


<PAGE>


            1.2 Conversion Right. In lieu of exercising this Warrant as
specified in Section 1.1, Holder may from time to time convert this Warrant, in
whole or in part, into a number of Shares determined by dividing (a) the
aggregate fair market value of the Shares or other securities otherwise issuable
upon exercise of this Warrant minus the aggregate Exercise Price of such Shares
by (b) the fair market value of one Share. The fair market value of the Shares
shall be determined pursuant to Section 1.4.

            1.3 Fair Market Value.

                  1.3.1 If shares of the Class (or shares of the Company's stock
into which shares of the Class are convertible or exchangeable) are traded on a
nationally recognized securities exchange or the over the counter market, the
fair market value of a Share shall be the closing price of a share of the Class
(or the closing price of a share of the Company's stock for which shares of the
Class are convertible or exchangeable) reported for the business day immediately
before Holder delivers its Notice of Exercise to the Company.

                  1.3.2 If shares of the Class (or shares of the Company's stock
into which shares of the Class are convertible or exchangeable) are not traded
on a nationally recognized securities exchange or the over the counter market,
the Board of Directors of the Company shall determine fair market value in its
reasonable good faith judgment. The foregoing notwithstanding, if Holder advises
the Board of Directors in writing that Holder disagrees with such determination,
then the Company and Holder shall promptly agree upon a reputable investment
banking firm to undertake such valuation. If the valuation of such investment
banking firm is greater than 110% of the value as determined by the Board of
Directors, then all fees and expenses of such investment banking firm shall be
paid by the Company. In all other circumstances, such fees and expenses shall be
paid by Holder. The valuation determined by such investment banking firm shall
be conclusive in any event.

            1.4 Delivery of Certificate and New Warrant. Promptly after Holder
exercises or converts this Warrant, the Company at its sole expense shall
promptly deliver to Holder (i) certificates for the Shares acquired upon such
exercise, and (ii) if this Warrant has not been fully exercised or converted and
has not expired, a new warrant of like tenor representing the Shares for which
this Warrant is still exercisable.

            1.5 Replacement of Warrants. On receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and, in the case of loss, theft or destruction, on delivery of an
indemnity agreement reasonably satisfactory in form and amount to the Company
or, in the case of mutilation, on surrender and cancellation of this Warrant,
the Company at its expense shall execute and deliver, in lieu of this Warrant, a
new warrant of like tenor.


                                      -2-
<PAGE>

            1.6 Sale, Merger, or Consolidation of the Company.

                  1.6.1. "Acquisition". For the purpose of this Warrant,
"Acquisition" means any sale, assignment, transfer, exclusive license, or other
disposition of all or substantially all of the assets of the Company, or any
acquisition, reorganization, consolidation, or merger of the Company where the
holders of the Company's outstanding voting equity securities immediately prior
to the transaction beneficially own less than 50.1% of the outstanding voting
equity securities of the surviving or successor entity immediately following the
transaction.

                  1.6.2. Assumption of Warrant. Upon the closing of any
Acquisition the successor or surviving entity shall assume the obligations of
this Warrant, and this Warrant shall be exercisable for the same securities,
cash, and property as would be payable for the Shares issuable upon exercise of
the unexercised portion of this Warrant as if such Shares were outstanding on
the record date for the Acquisition and subsequent closing. The Exercise Price
shall be adjusted accordingly, and the Exercise Price and number and class of
Shares shall continue to be subject to adjustment from time to time in
accordance with the provisions hereof.

ARTICLE 2. ADJUSTMENTS TO THE SHARES.

            2.1 Dividends, Splits, Etc. If the Company declares or pays a
dividend on the outstanding shares of the Class A Common Stock, payable in Class
A Common Stock, other securities or any type of property, or subdivides the
outstanding Class A Common Stock into a greater amount of Class A Common Stock
of the outstanding shares, then upon exercise of this Warrant, for each Share
acquired, Holder shall receive, without cost to Holder, the total number and
kind of securities or property to which Holder would have been entitled had
Holder owned the Shares of record as of the date the dividend or subdivision
occurred.

            2.2 Reclassification, Exchange or Substitution. Upon any
reclassification, exchange, substitution, reorganization or other event that
results in a change of the number and/or class of the securities issuable upon
exercise or conversion of this Warrant, Holder shall be entitled to receive,
upon exercise or conversion of this Warrant, the number and kind of securities
and property that Holder would have received for the Shares if this Warrant had
been exercised immediately before such reclassification, exchange, substitution,
reorganization or other event. The Company or its successor shall promptly issue
to Holder a new warrant of like tenor for such new securities or other property.
The new warrant shall provide for adjustments which shall be as nearly
equivalent as may be practicable to the adjustments provided for in this Article
2 including, without limitation, adjustments to the Exercise Price and to the
number of securities or property issuable upon exercise of the new warrant. The
provisions of this Section 2.2 shall similarly apply to successive
reclassifications, exchanges, substitutions, reorganizations or other events.

            2.3 Adjustments for Combinations, Etc. If the outstanding shares of
the Class are combined or consolidated, by reclassification or otherwise, into a
lesser number of shares, the


                                      -3-
<PAGE>

Exercise Price shall be proportionately increased and the number of Shares
issuable upon exercise or conversion of this Warrant is exercisable shall be
proportionately decreased.

            2.4 No Impairment. The Company shall not, by amendment of the
Certificate of Incorporation (the "Certificate") or its by-laws or through a
reorganization, transfer of assets, consolidation, merger, dissolution, issue,
or sale of securities or any other voluntary action, avoid or seek to avoid the
observance or performance of any of the terms to be observed or performed under
this Warrant by the Company, but shall at all times in good faith assist in
carrying out all of the provisions of this Article 2 and in taking all such
action as may be necessary or appropriate to protect Holder's rights under this
Article against impairment.

            2.5 Adjustments for Dilutive Issuances. In the event of the issuance
(a "Diluting Issuance") by the Company, after the Issue Date of this Warrant, of
Class A Common Stock at a price per share less than the Exercise Price or
securities convertible into Class A Common Stock at a conversion price per share
less than the Exercise Price, then the number of Shares issuable upon exercise
of this Warrant, shall be adjusted as a result of Diluting Issuances in
accordance with that certain Antidilution Agreement dated as of the date of this
Warrant, by and between Holder and the Company. Under no circumstances shall the
aggregate Exercise Price payable by Holder upon exercise of this Warrant
increase as a result of any adjustment arising from a Diluting Issuance.

            2.6 Fractional Shares. No fractional Shares shall be issuable upon
exercise or conversion of the Warrant and the number of Shares to be issued
shall be rounded down to the nearest whole Share. If a fractional Share interest
arises upon any exercise or conversion of this Warrant, the Company shall
eliminate such fractional Share interest by paying Holder an amount computed by
multiplying such fractional interest by the Fair Market Value (determined in
accordance with Section 1.3 above) of one Share.

            2.7 Certificate as to Adjustments. Upon each adjustment of the
Exercise Price, number of class of Shares or number of shares of Class A Common
Stock or other securities for which the Shares are convertible or exchangeable,
the Company at its expense shall promptly compute such adjustment, and furnish
Holder with a certificate of its chief financial officer setting forth such
adjustment and the facts upon which such adjustment is based. The Company shall
at any time and from time to time, upon written request, furnish Holder with a
certificate setting forth the Exercise Price, number and class of Shares and
conversion ratio in effect upon the date thereof and the series of adjustments
leading to such Exercise Price, number and class of Shares and conversion ratio.

ARTICLE 3. REPRESENTATIONS AND COVENANTS OF THE COMPANY.

            3.1 Representations and Warranties. The Company hereby represents
and warrants to the Holder as follows:


                                      -4-
<PAGE>

                  (a) All Shares which may be issued upon the due exercise of
this Warrant, and all Class A Common Stock or other securities, if any, issuable
upon due conversion of the Shares, shall, upon issuance, be duly authorized,
validly issued, fully paid and non-assessable, and free of any liens and
encumbrances except for restrictions on transfer provided for herein or under
applicable federal and state securities laws.

                  (b) The execution and delivery by the Company of this Warrant
and the performance of all obligations of the Company hereunder, including the
issuance to Holder of the right to acquire the Shares, have been duly authorized
by all necessary corporate action on the part of the Company, and this Warrant
Agreement is not inconsistent with the Certificate and/or the Company's by-laws,
does not contravene any law or governmental rule, regulation or order applicable
to it, does not and will not contravene any provision of, or constitute a
default under, any material indenture, mortgage, contract or other instrument to
which it is a party or by which it is bound, and constitutes a legal, valid and
binding agreement of the Company, enforceable in accordance with its terms.

                  (c) The authorized capital stock of the Corporation consists
of:

                        (i) 150,000,000 duly authorized shares of Class A Common
Stock, of which:

                              (A) 4,456,838 shares of Class A Common Stock are
outstanding;

                              (B) 10,122,602 shares of Class A Common Stock are
reserved for issuance upon the exercise of the warrants and outstanding options
listed on SCHEDULE 3.1(C) (whether or not presently exercisable);

                              (C) 79,000,000 shares of Class A Common Stock are
reserved for conversion of the Class B Common Stock; and,

                              (D) 41,200,000 shares of Class A Common Stock are
reserved for conversion of the Series A Preferred Shares.

                        (ii) 79,000,000 shares of Class B Common Stock, of which
28,105,150 shares are outstanding; and

                        (iii) 41,200,000 shares of Series A Preferred Stock, of
which 40,874,511 shares are outstanding.

                  (d) Schedule 3.1(c) sets forth all of the outstanding shares
of common stock and preferred stock and outstanding options, warrants,
convertible securities, convertible debentures, and rights to acquire, subscribe
for, and/or purchase any Class A Common Stock, preferred stock and/or other
capital stock of the Company or any securities or debentures


                                      -5-
<PAGE>

convertible into or exchangeable for Class A Common Stock, preferred stock
and/or other capital stock of the Company.

                  (e) The Company covenants that it shall at all times cause to
be reserved and kept available out of its authorized and unissued shares such
number of shares of its Class A Common Stock and other securities as will be
sufficient to permit the exercise in full of this Warrant.

            3.2 Notice of Certain Events. If the Company proposes at any time
(a) to declare any dividend or distribution upon any of its capital stock,
whether in cash, property, stock, or other securities and whether or not a
regular cash dividend; (b) to offer for subscription pro rata to the holders of
any class or series of its stock any additional shares of stock of any class or
series or other rights; (c) to effect any reclassification or recapitalization
of any of its securities; (d) to merge or consolidate with or into any other
corporation, or sell, lease, license, or convey all or substantially all of its
assets, or to liquidate, dissolve or wind up; or (e) offer holders of
registration rights the opportunity to participate in an underwritten public
offering of the Company's securities for cash, then, in connection with each
such event, the Company shall give Holder (1) at least 20 days prior written
notice of the date on which a record will be taken for such dividend,
distribution, or subscription rights (and specifying the date on which the
holders of securities of the Company shall be entitled to receive such dividend,
distribution or rights) or for determining rights to vote, if any, in respect of
the matters referred to in (c) and (d) above; (2) in the case of the matters
referred to in (c) and (d) above at least 20 days prior written notice of the
date when the same will take place (and specifying the date on which the holders
of securities of the Company will be entitled to exchange their securities of
the Company for securities or other property deliverable upon the occurrence of
such event); and (3) in the case of the matter referred to in (e) above, the
same notice as is given to the holders of such registration rights.

            3.3 Information Rights. So long as the Holder holds this Warrant
and/or any of the Shares, the Company shall deliver to the Holder (a) promptly
after mailing, copies of all notices or other written communications to the
shareholders of the Company, (b) within one-hundred and twenty (120) days after
the end of each fiscal year of the Company, the annual audited financial
statements of the Company certified by independent public accountants of
recognized standing and (c) such other financial statements required under and
in accordance with any loan documents between Holder and the Company or if there
are no such requirements (or if the subject loan(s) no longer are outstanding),
then within forty-five (45) days after the end of each of the first three
quarters of each fiscal year, the Company's quarterly, unaudited financial
statements.

            3.4 Registration Under Securities Act of 1933, as amended. The
shares of Class A Common Stock issuable upon conversion of the Shares (and the
Shares, at all times when the Class is Class A Common Stock) shall have certain
registration rights as set forth in that certain Registration Rights Agreement
of even date herewith between Holder and the


                                      -6-
<PAGE>

Company (the "Registration Rights Agreement"). The Company represents and
warrants to Holder that the Company's execution, delivery and performance of the
Registration Rights Agreement (a) has been duly authorized by all necessary
corporate action of the Company's Board of Directors and shareholders, (b) will
not violate the Certificate or the Company's by-laws, each as amended, (c) will
not violate or cause a breach or default (or an event which with the passage of
time or the giving of notice or both, would constitute a breach or default)
under any agreement, instrument, mortgage, deed of trust or other arrangement to
which the Company is a party or by which it or any of its assets is subject or
bound, and (d) does not require the approval, consent or waiver of or by any
shareholder, registration rights holder or other third party which approval,
consent or waiver has not been obtained as of the date of issuance of this
Warrant.

ARTICLE 4. MISCELLANEOUS.

            4.1 Automatic Conversion upon Expiration. In the event that, upon
the Expiration Date, the fair market value of one Share (or other security
issuable upon the exercise hereof) as determined in accordance with Section 1.4
above is greater than the Exercise Price in effect on such date, then this
Warrant shall automatically be deemed on and as of such date to be converted
pursuant to Section 1.2 above as to all Shares (or such other securities) for
which it shall not previously have been exercised or converted, and the Company
shall promptly deliver a certificate representing the Shares (or such other
securities) issued upon such conversion to the Holder.

            4.2 Legends. This Warrant and the Shares (and the securities
issuable, directly or indirectly, upon conversion of the Shares, if any) shall
be imprinted with a legend in substantially the following form:

      THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
      AMENDED, OR ANY STATE SECURITIES LAWS AND MAY NOT BE SOLD, PLEDGED OR
      OTHERWISE TRANSFERRED WITHOUT AN EFFECTIVE REGISTRATION THEREOF UNDER SUCH
      ACT AND LAWS, OR PURSUANT TO RULE 144 AND EXEMPTIONS UNDER APPLICABLE
      STATE SECURITIES LAWS, OR, SUBJECT TO SECTION 4.3 HEREOF, AN OPINION OF
      COUNSEL REASONABLY SATISFACTORY TO THE CORPORATION AND ITS COUNSEL THAT
      SUCH REGISTRATION IS NOT REQUIRED.

            4.3 Compliance with Securities Laws on Transfer. This Warrant and
the Shares (and the securities, if any, issued and issuable upon conversion of
the Shares) may not be transferred or assigned in whole or in part without
compliance with applicable federal and state securities laws by the transferor
and the transferee (including, without limitation, the delivery of investment
representation letters and legal opinions reasonably satisfactory to the
Company, as reasonably requested by the Company). The Company shall not require
Holder to provide an


                                      -7-
<PAGE>

opinion of counsel if the transfer is to Silicon Valley Bancshares (Holder's
parent company) or any other affiliate of Holder or if (a) there is no material
question as to the availability of current information as referenced in Rule
144(c), (b) Holder represents that it has complied with Rule 144(d) and (e) in
reasonable detail, (c) the selling broker represents that it has complied with
Rule 144(f), and (d) the Company is provided with a copy of Holder's notice of
proposed sale.

            4.4 Transfer Procedure. Following its receipt of this executed
Warrant, Silicon Valley Bank will transfer same in whole or in part to its
parent corporation, Silicon Valley Bancshares, and thereafter Holder and/or
Silicon Valley Bancshares may, subject to Section 4.3 above, transfer all or
part of this Warrant and/or the Shares (or the securities, if any, issued and
issuable upon conversion of the Shares) at any time and from time to time to The
Silicon Valley Bank Foundation or any other transferee by giving the Company
notice of the portion of the Warrant being transferred setting forth the name,
address and taxpayer identification number of the transferee and surrendering
this Warrant to the Company for reissuance to the transferee(s) (and Holder if
applicable); provided, that at all times prior to the Company's first public
offering of its common stock, Holder shall not, without the prior written
consent of the Company, transfer this Warrant (or any part hereof), any Shares,
or any securities issued or issuable upon conversion of the Shares, to any
person who directly competes with the Company, unless such transfer is in
connection with an Acquisition of the Company by any such person.

            4.5 Notices. All notices and other communications from the Company
to the Holder, or vice versa, shall be deemed delivered and effective when given
personally or mailed by first-class registered or certified mail, postage
prepaid, or sent via reputable overnight courier service, fee prepaid, at such
address as may have been furnished to the Company or the Holder, as the case may
be, in writing by the Company or such holder from time to time, but in all
cases, unless instructed in writing otherwise, the Company shall deliver a copy
of all notices to Holder to Silicon Valley Bank, Treasury Department, 3003
Tasman Drive, HA-200, Santa Clara, California 95054.

            4.6 Waiver. This Warrant and any term hereof may be changed, waived,
discharged or terminated only by an instrument in writing signed by the party
against which enforcement of such change, waiver, discharge or termination is
sought.

            4.7 Attorneys Fees. In the event of any dispute between the parties
concerning the terms and provisions of this Warrant, the party prevailing in
such dispute shall be entitled to collect from the other party all costs
incurred in such dispute, including reasonable attorneys' fees.

            4.8 Survival of Representations, Warranties and Agreements. All
representations and warranties of the Company contained herein shall survive the
date of this Warrant, the exercise or conversion of this Warrant (or any part
hereof) and/or the termination or expiration of rights hereunder. All agreements
of the Company contained herein shall survive indefinitely until, by their
respective terms, they are no longer operative.


                                      -8-
<PAGE>


            4.9 Governing Law. This Warrant shall be governed by and construed
in accordance with the laws of the State of Delaware, as such laws are applied
to agreements between Delaware residents entered into and to be performed
entirely within Delaware.

                                         "COMPANY"

                                         GREENFIELD ONLINE, INC.

                                         By:____________________________________

                                         Name:_________________________________
                                                (Print)
                                         Title: Chairman of the Board, President
                                                or Vice President

                                         By:____________________________________

                                         Name:_________________________________
                                                (Print)
                                         Title: Chief Financial Officer,
                                         Secretary, Assistant Treasurer or
                                         Assistant Secretary


                                      -9-

<PAGE>
                                   APPENDIX 1

                               NOTICE OF EXERCISE

     1. The undersigned hereby elects to purchase ____ shares of the
____________ stock of ________________ pursuant to Section 1.1 of the attached
Warrant, and tenders herewith payment of the Exercise Price of such shares in
full.

     1. The undersigned hereby elects to convert the attached Warrant into
Shares in the manner specified in Section 1.2 of the attached Warrant. This
conversion is exercised with respect to ___________ of shares of the
_______________ Stock of ___________________.

     [Strike paragraph that does not apply.]

     2. Please issue a certificate or certificates representing said shares in
the name of the undersigned or in such other name as is specified below:


                                    --------------------------------------------
                                         (Name)

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

                                    --------------------------------------------
                                         (Address)

     3. The undersigned represents it is acquiring the shares solely for its own
account and not as a nominee for any other party and not with a view toward the
resale or distribution thereof except in compliance with applicable securities
laws.


                                    --------------------------------------------
                                         (Signature)


---------------------------------
         (Date)



<PAGE>


                        Schedule 3.1(c) - Capitalization


Outstanding Capital Stock:


See attached Stock Ledger and Option Report



Outstanding options, warrants, convertible securities, convertible debentures,
and rights to acquire, subscribe for, and/or purchase any Class A Common Stock,
preferred stock and/or other capital stock of the Company or any securities or
debentures convertible into or exchangeable for Class A Common Stock, preferred
stock and/or other capital stock of the Company: