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LETTER OF TRANSMITTAL To accompany certificates representing shares of capital stock of nToggle, Inc.

The undersigned represents that I (we) have full authority to surrender without restriction the shares of capital stock of nToggle, Inc.

for exchange. You are hereby authorized and instructed to prepare in the name of and deliver to the address indicated below (unless

otherwise instructed in the boxes on the following page) a check or wire transfer payment representing a cash payment for shares

tendered pursuant to this Letter of Transmittal.

Method of delivery of the certificate(s) is at the option and risk of the owner thereof. See Instruction 1.

Mail or deliver this Letter of Transmittal representing your shares of capital stock of nToggle, Inc., to:

If delivering by mail:

American Stock Transfer & Trust Company,

LLC

Operations Center

Attn: Reorganization Department

P.O. Box 2042

New York, New York 10272-2042

If delivering by hand or courier:

American Stock Transfer & Trust Company,

LLC

Operations Center

Attn: Reorganization Department

6201 15th

Avenue

Brooklyn, New York 11219

For assistance call (877) 248-6417 or (718) 921-8317

Via Facsimile (718) 234-5001

Pursuant to the proposed merger under which Caviar Acquisition Corp., a wholly-owned subsidiary of The Rubicon Project, Inc., will

merge with and into nToggle, Inc., the undersigned encloses herewith and surrenders the following shares of capital stock of nToggle,

Inc.:

Name(s) and Address of Registered Holder(s) If there is any error in the name or address shown below, please make the

necessary corrections

DESCRIPTION OF SECURITIES SURRENDERED

(Please fill in. Attach separate schedule if needed)

Total Warrant Shares

Total Shares of Series A Preferred Stock

Total Shares of Series A-1 Preferred Stock

Total Shares of Company Common Stock

The instructions accompanying this Letter of Transmittal should be read carefully before this Letter of Transmittal is completed.

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LETTER OF TRANSMITTAL

FOR ISSUED AND OUTSTANDING SHARES OF

COMMON STOCK

SERIES A PREFERRED STOCK

SERIES A-1 PREFERRED STOCK

AND WARRANTS

OF

nToggle, Inc.

This Letter of Transmittal is for use by registered holders (the “Holders”) of shares of Common Stock of nToggle, Inc., a Delaware

corporation (the “Company” and such shares of the Company, the “Common Stock”), shares of Series A Preferred Stock of the

Company (“Series A Preferred Stock”), shares of Series A-1 Preferred Stock of the Company (“Series A-1 Preferred Stock” and

together with the shares of Common Stock and Series A Preferred Stock, the “Shares”) and vested warrants to purchase Shares of the

Company (the “Warrants”) for the deposit of evidence representing Shares and Warrants in connection with the proposed merger

pursuant to the Delaware General Corporation Law (the “Merger”), under which, among other things, Caviar Acquisition Corp.

(“Merger Sub”), a wholly owned subsidiary of The Rubicon Project, Inc. (“Parent”), will merge with and into the Company, with the

Company being the surviving corporation (the “Surviving Corporation”) and thereby becoming a wholly owned subsidiary of Parent,

pursuant to the Agreement and Plan of Merger by and among Parent, Company, Merger Sub, Shareholder Representative Services

LLC, a Colorado limited liability company solely in its capacity as holder representative, and the Persons delivering Joinder

Agreements therewith (the “Merger Agreement”), to be exchanged for the applicable portion of the Merger Consideration, as set forth

in the Merger Agreement. Capitalized terms used but not defined in this Letter of Transmittal have the meanings set out in the Merger

Agreement.

At the Effective Time of the Merger, each Share and Warrant shall be converted into the right to receive the applicable portion of the

Merger Consideration as follows, in each case, except as otherwise contemplated by the Merger Agreement:

(a) Each share of Series A Preferred Stock issued and outstanding immediately prior to the Effective Time (other than

Cancelled Shares and any Dissenting Shares) shall be converted into the right to receive the Series A Per Share

Closing Consideration, subject to the terms and conditions specified herein and in the Escrow Agreement. A portion

of the Series A Per Share Closing Consideration shall be deposited into each of the Adjustment Escrow Fund, the

Indemnity Escrow Fund and the Holder Representative Fund.

(b) Each share of Series A-1 Preferred Stock issued and outstanding immediately prior to the Effective Time (other than

Cancelled Shares and any Dissenting Shares) shall be converted into the right to receive the Series A-1 Per Share

Closing Consideration, subject to the terms and conditions specified herein and in the Escrow Agreement. A portion

of the Series A-1 Per Share Closing Consideration shall be deposited into each of the Adjustment Escrow Fund and

the Indemnity Escrow Fund and the Holder Representative Fund.

(c) Each share of Company Common Stock issued and outstanding immediately prior to the Effective Time (other than

Cancelled Shares and any Dissenting Shares) shall be converted into the right to receive the Common Per Share

Closing Consideration, subject to the terms and conditions specified herein and in the Escrow Agreement. A portion

of the Common Per Share Closing Consideration shall be deposited into each of the Adjustment Escrow Fund and

the Indemnity Escrow Fund and the Holder Representative Fund.

(d) Each Warrant will be exercised or deemed exercised pursuant to the terms thereof, and the Company shall issue in

full the Shares issuable pursuant thereto. Such Shares shall be converted into the right to receive a portion of the

Merger Consideration as provided in Section 2.7(a) of the Merger Agreement. At the Effective Time, to the extent

not prohibited by applicable Law, each Warrant that is not so exercised or deemed exercised shall be cancelled

without consideration and shall be of no further force and effect

The Series A, Series A-1 or Common Per Share Closing Consideration shall be deposited by Parent with the Exchange Agent, the

Holder Representative or the Escrow Agent as applicable on behalf of such Holder pursuant to the Merger Agreement, the Escrow

Agreement or Exchange Agent Agreement, and released by the Exchange Agent, the Holder Representative or the Escrow Agent in

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accordance with the terms and subject to the conditions of the Merger Agreement, the Escrow Agreement, or the Exchange Agent

Agreement as applicable.

All such payments to Holders will be subject to any applicable withholdings.

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TO: NTOGGLE, INC.

AND TO: THE RUBICON PROJECT, INC.

AND TO: CAVIAR ACQUISITION CORP.

AND TO: AMERICAN STOCK TRANSFER & TRUST COMPANY, LLC (the “Exchange Agent”)

The undersigned transmits herewith the certificate(s) described on the first page of this letter of transmittal for cancellation upon the

Merger becoming effective. The undersigned represents and warrants that the undersigned has good and sufficient authority to

execute and deliver this Letter of Transmittal and deposit, sell and transfer the Shares and Warrants represented by the enclosed

certificate(s) free from all liens, charges, encumbrances, claims and equities (such Shares and Warrants the “Deposited Securities”).

The undersigned acknowledges that, until surrendered as contemplated by the terms and subject to the conditions of the Merger

Agreement and this Letter of Transmittal, the Deposited Securities shall be deemed, at any time after the Effective Time, to represent

only the right to receive the portion of the Merger Consideration payable in respect of the Deposited Securities represented thereby, in

cash without interest and subject to applicable withholding taxes, in accordance with the terms of the Merger Agreement. If any

distributions are made payable to or to the order of the undersigned after the Effective Time, then the Exchange Agent shall place and

hold such distributions and shall pay such distributions after the undersigned shall have surrendered all Deposited Securities.

The undersigned irrevocably constitutes and appoints the Exchange Agent and any other person designated by the Exchange Agent in

writing, the true and lawful agent, attorney and attorney-in-fact of the undersigned with respect to the Deposited Securities with full

power of substitution (such power of attorney, being coupled with an interest, being irrevocable) to execute and negotiate any checks

or other instruments representing any such distribution payable to or to the order of the undersigned.

The undersigned revokes any and all other authority, other than as granted in this Letter of Transmittal, whether as agent, attorney-in-

fact, attorney, proxy or otherwise, previously conferred or agreed to be conferred by the undersigned at any time with respect to the

Deposited Securities. No subsequent authority, whether as agent, attorney-in-fact, attorney, proxy or otherwise, will be granted with

respect to the Deposited Securities surrendered with this Letter of Transmittal.

The undersigned covenants and agrees to execute all such documents, transfers and other assurances as may be necessary or desirable

to exchange the Deposited Securities for the right to receive the portion of the Merger Consideration payable in respect of the

Deposited Securities.

Each authority conferred or agreed to be conferred by the undersigned in this Letter of Transmittal may be exercised during any

subsequent legal incapacity of the undersigned and all obligations of the undersigned in this Letter of Transmittal shall be binding

upon the heirs, personal representatives, successors and assigns of the undersigned.

Settlement with the undersigned will be made by the Exchange Agent either by wire transfer of immediately available U.S. funds or

by forwarding a check payable in U.S. funds (in accordance with the instructions of the undersigned in this Letter of Transmittal),

representing the cash consideration to which the undersigned is entitled. Unless otherwise directed in this Letter of Transmittal, the

payment will be issued in the name of the registered holder of the Deposited Securities. If payment is by wire transfer, the wire

transfer will be executed pursuant to the wire transfer instructions specified by the undersigned in this Letter of Transmittal. If

payment is by check, the check will be forwarded by first class mail to the undersigned at the address specified in this Letter of

Transmittal. If no address is specified, checks will be forwarded to the address of the undersigned as shown on the share register of

the Company.

If the Merger is not completed or proceeded with, the enclosed share certificate(s) and all other ancillary documents will be returned

forthwith to the undersigned at the address set out on the first page of this letter of transmittal unless a different address is specified by

the undersigned in the special delivery instructions box on the following page.

Upon deposit by Parent: (a) with the Exchange Agent of cash representing the cash payable at Closing pursuant to the Merger

Agreement; (b) with the Escrow Agent of cash equal in value to the Indemnity Escrow Amount; (c) with the Escrow Agent of cash

equal in value to the Adjustment Escrow Amount; (d) with the Holder Representative of cash equal in value to the Holder

Representative Amount; and (e) with the Exchange Agent, to the extent applicable, of cash equal in value to the Net Adjustment

Amount, Parent shall be fully and completely discharged from its obligation to pay the Closing Consideration, the Indemnity Escrow

Amount, the Adjustment Escrow Amount, the Holder Representative Amount and the Net Adjustment Amount. The rights of such

Holders shall be limited to receiving, subject to them providing duly completed and executed Letters of Transmittal: (i) the amount of

cash payable to such Holders as Closing Consideration without interest, in accordance with the Merger Agreement, the Consideration

Spreadsheet and the Exchange Agent Agreement; (ii) the amount of funds in the Adjustment Escrow Fund following determination of

the Net Adjustment Amount, in accordance with their respective Adjustment Pro Rata Percentages; (iii) the amount of funds in the in

the Indemnity Escrow Fund upon termination thereof pursuant to the Escrow Agreement, in accordance with their respective Pro Rata

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Percentages; (iv) the amount of funds in the in the Holder Representative Fund upon termination thereof pursuant to the Merger

Agreement, in accordance with their respective Pro Rata Percentages; and (v) their remaining rights under the Merger Agreement, in

each case, subject to any applicable withholding taxes.

It is understood that the undersigned will not receive payment in respect of the Deposited Securities until the Merger is consummated

and until the certificate(s) representing the Deposited Securities owned by the undersigned are received by the Exchange Agent at the

address set out below, together with such additional documents as the Exchange Agent may require (including this Letter of

Transmittal and Joinder Agreement), and until the same are processed for payment by the Exchange Agent. It is further understood

that no interest will accrue on the purchase price payable pursuant to the Merger for the Deposited Securities.

* * *

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���� Check this box if your certificate(s) has been lost, stolen, misplaced or mutilated. See Instruction 5 on the reverse side of this

form.

SPECIAL PAYMENT INSTRUCTIONS

SPECIAL DELIVERY INSTRUCTIONS

Complete ONLY if the check is to be issued in a name which differs from the

name on the surrendered certificate(s). Issue to:

Name: ____________________________________________

Address: ____________________________________________

____________________________________________

____________________________________________

____________________________________________

(Please also complete the enclosed IRS Form W-9 (or the applicable IRS Form W-

8) AND

see instructions regarding signature guarantee. See Instructions 3, 4, 6 and 7)

Complete ONLY if check is to be mailed to some address other than the

address reflected above. See Instructions 4. Mail to:

Name: _______________________________________

Address: _______________________________________

_______________________________________

_______________________________________

_______________________________________

_______________________________________

PAYMENT BY WIRE TRANSFER

(to be completed only if the cash payment is to be made by wire transfer; if not completed, cash payment will be issued by check):

WIRE TRANSFER INSTRUCTIONS SPECIAL PAYMENT INSTRUCTIONS

Fill in ONLY if you desire funds to be delivered to you by wire transfer.

Bank Name:

Bank Address:

ABA No./Swift Code:

Account Name:

Account No.:

Reference:

Complete ONLY if the wire transfers representing the cash payment are to be

made to an account name that differs from the name(s) on the Surrendered

certificate(s).* Transfer to:

Bank Name:

Bank Address:

ABA No./Swift Code:

Account Name:

Account No.:

Reference:

Tax Identification/Social Security Number: :

* Requires signature guarantee. Please also complete the enclosed IRS Form W-9

(or the applicable IRS Form W-8) AND see instructions regarding signature

guarantee. See Instructions 3, 4, 6 and 7)

[signature boxes on next page]

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YOU MUST SIGN IN THE BOX BELOW AND PROVIDE YOUR TAX ID NUMBER ON THE BACK OF THIS FORM SIGNATURE(S) REQUIRED

Signature(s) of Registered Holder(s) or Agent

SIGNATURE(S) GUARANTEED (IF REQUIRED)

See Instruction 3. Must be signed by the registered holder(s) EXACTLY as name(s) appear(s) on

stock certificate(s). If signature is by a trustee, executor, administrator, guardian,

attorney-in-fact, officer for a corporation acting in a fiduciary or representative

capacity, or other person, please set forth full title. See Instructions 2, 3 and 7.

____________________________________________________ Signature of Registered Holder

____________________________________________________ Name of Registered Holder

____________________________________________________ Title, if any

Date: ________________

Phone No.: _____________________

Unless the shares are tendered by the registered holder(s) of the common

stock, or for the account of a participant in the Securities Transfer Agent’s

Medallion Program (“STAMP”), Stock Exchange Medallion Program

(“SEMP”) or New York Stock Exchange Medallion Signature Program

(“MSP”) (an “Eligible Institution”), the signature(s) must be guaranteed by

an Eligible Institution. See Instruction 3. __

____________________________________________ Authorized Signature

_

_____________________________________________ Name of Firm

______________________________________________ Address of Firm - Please Print

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INSTRUCTIONS FOR SURRENDERING CERTIFICATES (Please read carefully the instructions below)

1. Method of Delivery: Your old certificate(s) and the Letter of Transmittal must be sent or delivered to American Transfer & Trust

Company, LLC (the “Exchange Agent”). Do not send your certificates to nToggle, Inc. or The Rubicon Project, Inc. The method of delivery of certificates to be surrendered to the Exchange Agent at the address set forth on the front of this Letter of Transmittal is at the option and risk of the surrendering shareholder. Delivery will be deemed effective only when received. If you submit this Letter of Transmittal by facsimile, you must also send or deliver your certificate(s) in order to receive payment. If the certificate(s) are sent by mail, registered mail with return receipt requested and proper insurance is suggested.

2. Payment in the Same Name: If the cash and shares are issued in the same name as the surrendered certificate is registered, the Letter of Transmittal should be completed and signed exactly as the surrendered certificate is registered. Do not sign the share certificate(s). Signature guarantees are not required if the certificate(s) surrendered herewith are submitted by the registered owner of such securities who has not completed the section entitled “Special Payment Instructions” or are for the account of an Eligible Institution. If any of the securities surrendered hereby are owned by two or more joint owners, all such owners must sign this Letter of Transmittal exactly as written on the face of the certificate(s). If any securities are registered in different names on several certificates, it will be necessary to complete, sign and submit as many separate Letters of Transmittal as there are different registrations. Letters of Transmittal executed by trustees, executors, administrators, guardians, attorneys-in-fact, officers of corporations, or others acting in a fiduciary capacity who are not identified as such in the registration must be accompanied by proper evidence of the signer's authority to act.

3. Payment in Different Name: If the section entitled “Special Payment Instructions” is completed, then signatures on this Letter of Transmittal must be guaranteed by a firm that is a bank, broker, dealer, credit union, savings association or other entity that is an Eligible Institution. If the surrendered certificates are registered in the name of a person other than the signer of this Letter of Transmittal, or if payment is to be made to a person other than the signer of this Letter of Transmittal, or if the payment is to be made to a person other than the registered owner(s), then the surrendered certificates must be endorsed or accompanied by duly executed stock powers, in either case signed exactly as the name(s) of the registered owners appear on such certificate(s) or stock power(s), with the signatures on the certificate(s) or stock power(s) guaranteed by an Eligible Institution as provided herein.

4. Special Payment and Delivery Instructions: Indicate the name in which and address to which the check and written confirmation of the electronic issuance of shares are to be sent if different from the name and/or address of the person(s) signing this Letter of Transmittal. If Special Payment Instructions have been completed, an IRS Form W-9 (or applicable IRS Form W-8) must also be completed for the person named therein, and that person will be considered the record owner.

5. Letter of Transmittal Required; Surrender of Certificate(s); Lost Certificate(s): You will not receive your wire transfer or check and written confirmation of the electronic issuance of shares unless and until you deliver (i) a duly executed Joinder Agreement to the Company and (ii) this Letter of Transmittal, properly completed and duly executed, to the Exchange Agent, together with the certificate(s) evidencing your securities and any required accompanying evidences of authority. If your certificate(s) has been lost, stolen, misplaced or destroyed, contact the Exchange Agent for instructions at (877) 248-6417 or (718) 921-8317 prior to submitting your certificates for exchange. Any nToggle, Inc. shareholder who has lost certificates should make arrangements (which may include the posting of a bond or other satisfactory indemnification and an affidavit of loss) to replace lost certificates. Such arrangements should be made with the Exchange Agent.

6. Backup Withholding: Under the federal income tax law, in order to avoid backup withholding, you are required to provide the Exchange Agent with (i) your correct Taxpayer Identification Number (“TIN”) and certain other information on the enclosed IRS Form W-9 (if you are a “United States person” for U.S. federal income tax purposes) or (ii) certain information on the applicable, properly completed, IRS Form W-8 (if you are not a “United States person” for U.S. federal income tax purposes). If the certificate(s) are in more than one name or are not in the name of the actual owner, or for additional details on what TIN to provide the Exchange Agent, consult the enclosed instructions to the IRS Form W-9 for additional guidance on which number to report. Failure to provide the appropriate information on the IRS Form W-9 (or the applicable IRS Form W-8) may subject you to backup withholding at the current statutorily imposed rate (currently 28%) on any reportable payment made to you pursuant to the Merger.

7. Share Transfer Taxes. If payment is to be made to any person other than the registered holder, or if surrendered certificates are

registered in the name of any person other than the person(s) signing the Letter of Transmittal, the amount of any share transfer taxes (whether imposed on the registered holder or such person) payable as a result of the transfer to such person will be deducted from the payment for such securities if satisfactory evidence of the payment of such taxes, or exemption therefrom, is not submitted. Except as provided in this Instruction 7, it will not be necessary for transfer tax stamps to be affixed to the certificates listed in the Letter of Transmittal.

All questions as to the validity, form and eligibility of any surrender of certificates will be determined by the Exchange Agent and The Rubicon Project, Inc. and such determination shall be final and binding. Exchange Agent and The Rubicon Project, Inc. reserve the right to waive any irregularities or defects in the surrender of any certificates. A surrender will not be deemed to have been made until all irregularities have been cured or waived.

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IMPORTANT TAX INFORMATION

Under current U.S. federal income tax law, a Holder who tenders certificates representing securities that are

accepted for exchange may be subject to backup withholding. In order to avoid such backup withholding, a Holder who is

a “U.S. person” for federal income tax purposes must provide the Exchange Agent with such Holder’s correct TIN and

certify that such Holder is not subject to such backup withholding by completing the IRS Form W-9 provided herewith.

In general, if such Holder is an individual, the TIN is the Social Security number of such individual. A Holder who is not

a “U.S. person” for federal income tax purposes must provide the Exchange Agent with an appropriate, properly

completed IRS Form W-8, which can be obtained from the Exchange Agent or online at www.irs.gov. If the Exchange

Agent is not provided with a properly completed IRS Form W-9 or IRS Form W-8, reportable payments made pursuant to

the Merger may be subject to backup withholding, and the Holder may be subject to various penalties. For further

information concerning backup withholding and instructions for completing the IRS Form W-9 (including how to obtain a

taxpayer identification number if you do not have one and how to complete the IRS Form W-9 if the certificates

representing securities are held in more than one name), consult the enclosed instructions to the IRS Form W-9. For

further information concerning instructions for completing the appropriate IRS Form W-8, consult the instructions to the

appropriate IRS Form W-8, which can be obtained from the Exchange Agent or through the Internal Revenue Service

website at www.irs.gov.

Certain Holders (including, among others, certain corporations and certain foreign individuals) are not subject to

these backup withholding and reporting requirements. In order to avoid erroneous backup withholding, exempt Holders

who are “U.S. persons” for federal income tax purposes should complete the IRS Form W-9 by providing his, her or its

correct TIN, signing and dating the form and entering the correct exempt payee code in Box 4. Exempt Holders who are

not “U.S. persons” for federal income tax purposes should submit an appropriate, properly completed Form W-8, signed

under penalties of perjury, attesting to their exempt status. IRS Forms W-8 can be obtained from the Exchange Agent or

through the Internal Revenue Service website at www.irs.gov.

Backup withholding is not an additional tax. Rather, the federal income tax liability of a person subject to backup

withholding will be reduced by the amount of tax withheld. If withholding results in an overpayment of taxes, a refund

may be obtained provided that the required information is timely furnished to the Internal Revenue Service.

NOTE: FAILURE TO COMPLETE AND RETURN THE IRS FORM W-9 (OR APPROPRIATE IRS

FORM W-8) MAY RESULT IN BACKUP WITHHOLDING OF A PORTION OF ANY PAYMENTS MADE TO

YOU PURSUANT TO THE MERGER. PLEASE REVIEW THE INSTRUCTIONS TO IRS FORM W-9 (OR

THE INSTRUCTIONS TO THE APPROPRIATE IRS FORM W-8) FOR ADDITIONAL DETAILS.

All Holders are urged to consult their own tax advisors to determine whether they are exempt from these

backup withholding and reporting requirements and to determine which form should be used to avoid backup

withholding.

Please note that the foregoing certifications do not exempt any holder from any compensation-related

withholdings that may be required. Any payment of the Merger Consideration that is treated as wages for tax purposes

will be subject to the withholding requirements that are applicable to wages, regardless of the submission of an IRS Form

W-9 or IRS Form W-8.

Taxes withheld from amounts payable in connection with the Merger Agreement will be treated for all purposes of

the Merger Agreement as having been paid to the persons with respect to whom such amounts were withheld.

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