<PAGE>
                                                                Exhibit 9.1



                              VOTING AGREEMENT

     VOTING AGREEMENT, dated as of November 23, 1998 (this "Voting 
Agreement"), by and among America Online, Inc., a Delaware corporation 
("Acquiror"), and each of the parties identified on Schedule A hereto 
(individually a "Stockholder" and collectively the "Stockholders").

     WHEREAS, Netscape Communications Corporation, a Delaware corporation 
("Company"), Acquiror and Apollo Acquisition Corp., a Delaware corporation 
and a newly-formed wholly owned direct subsidiary of Acquiror ("Newco"), have 
contemporaneously with the execution of this Voting Agreement, entered into 
an Agreement and Plan of Merger dated as of November 23, 1998 (the "Merger 
Agreement") which provides, among other things, that Newco shall be merged 
(the "Merger") with and into the Company pursuant to the terms and conditions 
thereof;

     WHEREAS, as an essential condition and inducement to Acquiror to enter 
into the Merger Agreement and in consideration therefor, the undersigned 
Stockholders and the Acquiror have agreed to enter into this Voting 
Agreement; and

     WHEREAS, as of the date hereof, the Stockholders own of record and 
beneficially the shares of common stock, par value $0.0001 per share, of the 
Company (the "Company Common Stock") set forth opposite their respective 
names on Schedule A hereto and desire to enter into this Agreement with 
respect to such shares of Company Common Stock;

     NOW, THEREFORE, in consideration of the foregoing and the mutual 
covenants and agreements contained herein and in the Merger Agreement, and 
for other good and valuable consideration, the receipt and sufficiency of 
which are hereby acknowledged, and intending to be legally bound hereby, the 
parties hereto hereby agree as follows:

<PAGE>

                                     ARTICLE I

                                  Voting of Shares

          Section 1.1    VOTING AGREEMENT.  Each Stockholder hereby agrees to 
(a) appear, or cause the holder of record on any applicable record date (the 
"Record Holder") to appear for the purpose of obtaining a quorum at any 
annual or special meeting of stockholders of the Company and at any 
adjournment thereof at which matters relating to the Merger, Merger Agreement 
or any transaction contemplated thereby are considered and (b) vote, or cause 
the Record Holder to vote, in person or by proxy all of the shares of the 
Company Common Stock owned by Stockholder, or with respect to which such 
Stockholder has or shares voting power or control, and all of the shares of 
Company Common Stock which shall, or with respect to which voting power or 
control shall, hereafter be acquired by such Stockholder (collectively, the 
"Shares") in favor of the Merger, the Merger Agreement and the transactions 
contemplated by the Merger Agreement.

          Section 1.2    NO OWNERSHIP INTEREST.  Nothing contained in this 
Voting Agreement shall be deemed to vest in Acquiror any direct or indirect 
ownership or incidence of ownership of or with respect to any Shares.  All 
rights, ownership and economic benefits of and relating to the Shares shall 
remain and belong to the Stockholders, and Acquiror shall have no authority 
to manage, direct, superintend, restrict, regulate, govern, or administer any 
of the policies or operations of the Company or exercise any power or 
authority to direct the Stockholders in the voting of any of the Shares, 
except as otherwise provided herein, or the performance of the Stockholders' 
duties or responsibilities as stockholders of the Company.

          Section 1.3    EVALUATION OF INVESTMENT.  Each Stockholder, by 
reason of its knowledge and experience in financial and business matters, 
believes itself capable of evaluating the merits and risks of the investment 
in shares of common stock, par value $.01 per share, of Acquiror ("Acquiror 
Common Stock"), contemplated by the Merger Agreement.

          Section 1.4    DOCUMENTS DELIVERED.  Each Stockholder acknowledges 
receipt of copies of the following documents:

               (a)  the Merger Agreement and all Annexes thereto;

               (b)  the Option Agreement;

                                       2
<PAGE>

               (c)  Acquiror's Annual Report on Form 10-K for the fiscal year
                    ended June 30, 1998;

               (d)  Acquiror's Proxy Statement dated September 28, 1998; and

               (e)  each report filed with the Securities and Exchange
                    Commission by the Acquiror on Forms 8-K and 10-Q since June
                    30, 1998.

Each Stockholder also acknowledges that he possesses the information relating 
to the Company which he deems relevant to his investment in the Acquiror 
Common Stock should the Merger be consummated.

          Section 1.5    NO INCONSISTENT AGREEMENTS.  Each Stockholder hereby 
covenants and agrees that, except as contemplated by this Voting Agreement 
and the Merger Agreement, the Stockholder (a) has not entered, and shall not 
enter at any time while this Voting Agreement remains in effect, into any 
voting agreement and (b) has not granted, and shall not grant at any time 
while this Voting Agreement remains in effect, a proxy or power of attorney, 
in either case which is inconsistent with this Agreement.

                                   ARTICLE II

                                    Transfer

          Section 2.1    TRANSFER OF TITLE.

                    (a)  Each Stockholder hereby covenants and agrees that such
                         Stockholder will not, prior to the termination of this
                         Voting Agreement, either directly or indirectly, offer
                         or otherwise agree to sell, assign, pledge,
                         hypothecate, transfer, exchange, or dispose of any
                         Shares or options to purchase Company Common Stock
                         ("Options") or any other securities or rights
                         convertible into or exchangeable for shares of Company
                         Common Stock, owned either directly or indirectly by
                         such Stockholder or with respect to which such
                         Stockholder has the power of disposition, 

                                       3
<PAGE>

                         whether now or hereafter acquired, without the prior 
                         written consent of Acquiror (provided nothing 
                         contained herein will be deemed to restrict the 
                         exercise of Options), unless the Person to whom 
                         Shares or Options have been sold, assigned, pledged, 
                         hypothecated, transferred, exchanged or disposed 
                         agrees to be bound by this Voting Agreement as if a 
                         party hereto.

                    (b)  The Stockholder hereby agrees and consents to the entry
                         of stop transfer instructions by the Company against
                         the transfer of any Shares consistent with the terms of
                         Section 2.1(a) hereof.

                                    ARTICLE III

                           Representations and Warranties
                                of the Stockholders

     Each Stockholder hereby severally and not jointly represents and warrants
to Acquiror as follows:

          Section 3.1    AUTHORITY RELATIVE TO THIS AGREEMENT.  Such 
Stockholder is competent to execute and deliver this Voting Agreement, to 
perform its obligations hereunder and to consummate the transactions 
contemplated hereby. This Voting Agreement has been duly and validly executed 
and delivered by such Stockholder and, assuming the due authorization, 
execution and delivery by Acquiror, constitutes a legal, valid and binding 
obligation of such Stockholder, enforceable against such Stockholder in 
accordance with its terms.

          Section 3.2    NO CONFLICT.  The execution and delivery of this 
Voting Agreement by such Stockholder does not, and the performance of this 
Voting Agreement by such Stockholder shall not, result in any breach of or 
constitute a default (or an event that with notice or lapse of time or both 
would become a default) under, or give to others any rights of termination, 
amendment, acceleration or cancellation of, or result in the creation of a 
lien or encumbrance, on any of the Shares or Options pursuant to, any note, 
bond, mortgage, indenture, contract, agreement, lease, license, permit, 
franchise or other instrument or obligation to which such Stockholder is a 
party or by which such Stockholder or the Shares or Options are bound or 
affected.

                                       4
<PAGE>


          Section 3.3    TITLE TO THE SHARES.  The Shares and Options held by 
such Stockholder are owned free and clear of all security interests, liens, 
claims, pledges, options, rights of first refusal, agreements, limitations on 
such Stockholder's voting rights, charges and other encumbrances of any 
nature whatsoever, and such Stockholder has not appointed or granted any 
proxy, which appointment or grant remains effective, with respect to the 
Shares.

                                     ARTICLE IV

                                   Miscellaneous

          Section 4.1    NO SOLICITATION.  From the date hereof until the 
Effective Time or, if earlier, the termination of the Merger Agreement, the 
Stockholder shall not (whether directly or indirectly through advisors, 
agents or other intermediaries) (a) solicit, initiate or encourage any 
Acquisition Proposal or (b) engage in discussions or negotiations with, or 
disclose any non-public information relating to the Company or its 
Subsidiaries to any Person that has made an Acquisition Proposal or has 
advised the Stockholder, or to his Knowledge, any other Stockholder or the 
Company, that such Person is interested in making an Acquisition Proposal.

          Section 4.2    TERMINATION.  This Agreement shall terminate upon 
the earliest to occur of (a) the termination of the Merger Agreement in 
accordance with its terms or (b) the Effective Time.  Upon such termination, 
no party shall have any further obligations or liabilities hereunder, 
provided that no such termination shall relieve any party from liability for 
any breach of this Voting Agreement prior to such termination.

          Section 4.3    ENFORCEMENT OF AGREEMENT.  The parties hereto agree 
that irreparable damage would occur in the event that any of the provisions 
of this Voting Agreement were not performed in accordance with its specified 
terms or were otherwise breached.  It is accordingly agreed that the parties 
shall be entitled to an injunction or injunctions to prevent breaches of this 
Voting Agreement and to specific performance of the terms and provisions 
hereof in addition to any other remedy to which they are entitled at law or 
in equity.

          Section 4.4    SUCCESSORS AND AFFILIATES.  This Voting Agreement shall
inure to the benefit of and shall be binding upon the parties hereto and their

                                       5
<PAGE>

respective heirs, legal representatives and permitted assigns.  If any 
Stockholder shall at any time hereafter acquire ownership of, or voting power 
with respect to, any additional Shares in any manner, whether by the exercise 
of any Options or any securities or rights convertible into or exchangeable 
for shares of Company Common Stock, by operation of law or otherwise, such 
Shares shall be held subject to all of the terms and provisions of this 
Voting Agreement.  Without limiting the foregoing, each Stockholder 
specifically agrees that the obligations of such Stockholder hereunder shall 
not be terminated by operation of law, whether by death or incapacity of the 
Stockholder or otherwise.

          Section 4.5    ENTIRE AGREEMENT.  This Voting Agreement together 
with the Affiliate's Agreements, in the form attached as Annex C to the 
Merger Agreement, if and to the extent entered into by each of the 
Stockholders and Acquiror constitutes the entire agreement among Acquiror and 
the Stockholders with respect to the subject matter hereof and supersedes all 
prior agreements and understandings, both written and oral, among Acquiror 
and the Stockholders with respect to the subject matter hereof.

          Section 4.6    CAPTIONS AND COUNTERPARTS.  The captions in this 
Voting Agreement are for convenience only and shall not be considered a part 
of or affect the construction of interpretation of any provision of this 
Voting Agreement.  This Voting Agreement may be executed in several 
counterparts, each of which shall constitute one in the same instrument.

          Section 4.7    AMENDMENT.  This Voting Agreement may not be amended 
except by an instrument in writing signed by the parties hereto.

          Section 4.8    WAIVERS.  Except as provided in this Voting 
Agreement, no action taken pursuant to this Voting Agreement, including 
without limitation any investigation by or on behalf of any party, shall be 
deemed to constitute a waiver by the party taking such action of compliance 
with any representations, warranties, covenants or agreements contained in 
this Voting Agreement.  The waiver by any party hereto of a breach of any 
provision hereunder shall not operate or be construed as a wavier of any 
prior or subsequent breach of the same or any other provision hereunder.

          Section 4.9    SEVERABILITY.  If any term or other provision of 
this Voting Agreement is invalid, illegal or incapable of being enforced by 
any rule of law, or public policy, all other conditions and provisions of 
this Voting Agreement 

                                       6
<PAGE>

shall nevertheless remain in full force and effect.  Upon such determination 
that any term or other provision is invalid, illegal or incapable of being 
enforced, the parties hereto shall negotiate in good faith to modify this 
Voting Agreement so as to effect the original intent of the parties as 
closely as possible to the fullest extent permitted by applicable law in a 
mutually acceptable manner in order that the terms of this Voting Agreement 
remain as originally contemplated to the fullest extent possible.

          Section 4.10   NOTICES.  All notices and other communications given 
or made pursuant hereto shall be in writing and shall be deemed to have been 
duly given or made and shall be effective upon receipt, if delivered 
personally, upon receipt of a transmission confirmation if sent by facsimile 
(with a confirming copy sent by overnight courier) and on the next business 
day if sent by Federal Express, United Parcel Service, Express Mail or other 
reputable overnight courier to the parties at the following addresses (or at 
such other address for a party as shall be specified by notice):

               If to a Stockholder:

               At the address set forth opposite such Stockholder's name on
               Schedule A hereto

               With a copy to:

               Wilson Sonsini Goodrich & Rosati
               Professional Corporation
               650 Page Mill Road
               Palo Alto, California  94304-1050
               Attention:  Larry Sonsini, Jim Strawbridge
                           and Marty Korman
               Telephone:  (650) 493-9300
               Facsimile:  (650) 493-6811

               If to Acquiror or Newco:

               America Online, Inc.
               22000 AOL Way
               Dulles, Virginia  20166-9323
               Attention:  Stephen M. Case
                           President & CEO

                                       7
<PAGE>

               Facsimile No.:  (703) 265-1422

               with a copy to:

               Louis A. Goodman, Esq.
               Skadden, Arps, Slate, Meagher & Flom LLP
               One Beacon Street
               31st Floor
               Boston, Massachusetts  02108
               Telephone:  (617) 573-4800
               Fax:  (617) 573-4822

          Section 4.11   GOVERNING LAW.  This Voting Agreement shall be 
governed by, and construed in accordance with, the laws of the State of 
Delaware regardless of the laws that might otherwise govern under applicable 
principles of conflicts of law.

          Section 4.12   DEFINITIONS.  Capitalized terms used and not defined 
herein shall have the meaning set forth in the Merger Agreement.

          Section 4.13   OBLIGATIONS OF STOCKHOLDERS.  The obligations of the 
Stockholders hereunder shall be "several" and not "joint" or "joint and 
several."  Without limiting the generality of the foregoing, under no 
circumstances will any Stockholder have any liability or obligation with 
respect to any misrepresentation or breach of covenant of any other 
Stockholder.

          Section 4.14   OFFICERS AND DIRECTORS.  No person who is or becomes 
(during the term hereof) a director or officer of the Company makes any 
agreement or understanding herein in his or her capacity as such director or 
officer, and nothing herein will limit or affect, or give rise to any 
liability to Stockholder by virtue of, any actions taken by any Stockholder 
in his or her capacity as an officer or director of the Company in exercising 
its rights under the Merger Agreement.

          Section 4.15   INTERPRETATION.  The parties have participated 
jointly in the negotiation of this Voting Agreement.  In the event that an 
ambiguity or question of intent or interpretation arises, this Voting 
Agreement shall be construed as if drafted jointly by the parties, and no 
presumption or burden of proof shall arise favoring or disfavoring any party 
by virtue of the authorship of the provisions of this Voting Agreement.

                                       8
<PAGE>

     IN WITNESS WHEREOF, each of the parties hereto have caused this Voting 
Agreement to be duly executed as of the date first written above.

                              AMERICA ONLINE, INC.

                              By:     /s/ Kenneth J. Novack
                                 -------------------------------------
                                   Name:      Kenneth J. Novack
                                   Title:    Vice Chairman

                                         
                                 -------------------------------------
                                   Name:  James L. Barksdale

                                         
                                 -------------------------------------
                                   Name:  Marc L. Andreessen

                                          
                                 -------------------------------------
                                   Name:  James H. Clark





                         SIGNATURE PAGE TO VOTING AGREEMENT

<PAGE>

     IN WITNESS WHEREOF, each of the parties hereto have caused this Voting 
Agreement to be duly executed as of the date first written above.

                              AMERICA ONLINE, INC.

                              By:    
                                 -------------------------------------
                                   Name:     
                                   Title:    

                                          /s/ James L. Barksdale
                                 -------------------------------------
                                   Name:  James L. Barksdale

                                          /s/ Marc L. Andreessen
                                 -------------------------------------
                                   Name:  Marc L. Andreessen

                                          /s/ James H. Clark
                                 -------------------------------------
                                   Name:  James H. Clark





                         SIGNATURE PAGE TO VOTING AGREEMENT


<PAGE>

                                   MARC L. ANDREESSEN LIVING TRUST
                                   DTD 02/01/96

                                   By:  /s/ Marc L. Andreessen
                                      --------------------------------
                                        Marc L. Andreessen, Trustee


                                   ANDREESSEN 1996 CHARITABLE
                                   REMAINDER TRUST DTD 2/01/96

                                   By:  
                                      --------------------------------
                                        Michael G. Mohr, Co-Trustee

                                   By:  /s/ Marc L. Andreessen
                                      --------------------------------
                                        Marc L. Andreessen, Co-Trustee


                                   ANDREESSEN 1996 CHARITABLE
                                   REMAINDER TRUST DTD 2/21/96

                                   By:  
                                      --------------------------------
                                        Michael G. Mohr, Co-Trustee

                                   By:  /s/ Marc L. Andreessen
                                      --------------------------------
                                        Marc L. Andreessen, Co-Trustee


                                   MONACO PARTNERS LP

                                   By:        /s/ James H. Clark
                                      --------------------------------
                                        Name:  James H. Clark
                                        Title: President


                                   CLARK VENTURES INC.

                                   By:        /s/ James H. Clark
                                      --------------------------------
                                        Name:  James H. Clark
                                        Title: President


                                       
                      SIGNATURE PAGE TO VOTING AGREEMENT


<PAGE>

                                   MARC ANDREESSEN 1996 LIVING
                                   TRUST UTA DTD 2/1/96

                                   By:  /s/ Marc L. Andreessen
                                      --------------------------------
                                        Marc L. Andreessen, Trustee






                      SIGNATURE PAGE TO VOTING AGREEMENT