<PAGE>   1

Exhibit 10.15



                                       69

<PAGE>   2

                           TWELFTH AMENDMENT TO LEASE


           THIS TWELFTH AMENDMENT TO LEASE (the "Amendment") is made and entered
into as of the date below written by and between TODA DEVELOPMENT, INC., a
California corporation ("Landlord"), and MACROMEDIA, INC., a Delaware
corporation ("Tenant").

RECITALS

           A. Landlord and Tenant are parties to that certain lease dated June
27, 1991 for certain premises on the third floor of the building commonly known
as 600 Townsend Street, San Francisco, California, as amended by that certain
First Amendment to Lease dated May 4, 1992, the Second Amendment to Lease dated
August 9, 1994, the Third Amendment to Lease dated November 7, 1994, the Fourth
Amendment to Lease dated April 6, 1995, the Fifth Amendment to Lease dated
August 31, 1995, the Sixth Amendment to Lease dated October 31, 1995, the
Seventh Amendment to Lease dated December 15, 1995, the Eighth Amendment to
Lease dated January 25, 1996, the Ninth Amendment to Lease dated February 21,
1996, the Tenth Amendment to Lease dated April 30, 1996 and the Eleventh
Amendment to Lease dated June 13, 1996 (collectively, the "Lease"). Tenant's
predecessor-in-interest under the Lease was Macromind, Inc.

           B. Landlord and Tenant desire to amend the Lease as set forth below.


AGREEMENT

           Landlord and Tenant hereby agree as follows:

           1. ADDITIONAL PREMISES. Commencing as of April 1, 1997 (the
"Additional Premises Rental Commencement Date") the Premises shall include that
portion of the fifth floor of the Building comprising approximately 21,766
rentable square feet as shown on EXHIBIT A attached hereto (the "Additional
Premises"). The total rentable square footage of the Premises, including the
Additional Premises, shall be approximately 117,255 as shown on EXHIBIT B.



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<PAGE>   3

           2. DELIVERY OF ADDITIONAL PREMISES. Landlord shall deliver possession
of the Additional Premises as of April 1, 1997. If Landlord is unable to deliver
possession as of April 1, 1997, Landlord shall not be liable for any damage
caused for failing to deliver possession, and this Amendment shall not be void
or voidable. The Additional Premises Rental Commencement Date shall be delayed
until Landlord delivers possession of such space to Tenant. In the event that
the Additional Premises are delivered on other than April 1, 1997, Landlord and
Tenant shall execute a letter confirming the delivery date.

           3. RENTAL. Commencing upon the Additional Premises Rental
Commencement Date, monthly Base Rental under the Lease shall be as follows:

<TABLE>
<CAPTION>
             Period                                  Rental   
             ------                                  ------   
         <S>                                     <C>
         4/1/97 -  8/31/97                       $ 179,400.15 
         9/1/97 - 12/31/01                       $ 191,125.65 
         1/1/02 - 12/31/03                       $ 211,059.00 
         1/1/04 - 12/31/05                       $ 288,647.25 
</TABLE>

           4. ADDITIONAL TENANT IMPROVEMENT ALLOWANCE. Landlord shall provide
Tenant with an additional Tenant Improvement Allowance in the amount of $217,660
for the Additional Premises. Said allowance shall be paid and used for the
Additional Premises in accordance with paragraph 8 and Rider 5.C of the Lease.
Tenant may use its own contractor and architect (both subject to Landlord's
reasonable approval) for tenant improvement work in the Additional Premises. All
costs of design and construction shall be included within the above Allowance.

           4. TENANT'S PARTICIPATION. Commencing as of the Additional Premises
Rental Commencement Date, Tenant's Participation for purposes of paragraph 6
shall be determined by using a numerator of 117,255 rentable square feet. The
base year shall be 1997 for the Additional Rental payable by Tenant with respect
to the Additional Premises.

           5. CONDITION OF ADDITIONAL PREMISES; IMPROVEMENTS. Tenant accepts the
Additional Premises in their "as is" condition. Tenant shall be responsible for
all demolition of and improvements to such premises and shall comply with the
terms of the Lease with respect to all work undertaken by Tenant, including,
without limitation, paragraphs 8 and 9 thereof.

           6. UTILITIES. Paragraph 4 of the Lease shall apply with respect to
utilities for the Additional Premises.



                                       71

<PAGE>   4

           7. SECURITY DEPOSIT. The Security Deposit shall be increased by
$42,443.70 which sum shall be paid by Tenant upon execution of this Twelfth
Amendment and held in accordance with paragraph 5 of the Lease.

           8. PARKING. Upon delivery of the Additional Premises, Tenant shall
have the right to thirteen (13) additional parking spaces in the Building Garage
for a total of 75 spaces. The initial charge shall be $90 per month per space
for the additional stalls for the calendar year 1997. The charge shall increase
5% over the rate then in effect on each anniversary of the Additional Premises
Rental Commencement Date during the initial term of the Lease. The charge during
the option period shall be the Fair Market Value. Notwithstanding the foregoing,
if the garage becomes full Tenant shall be entitled only to one parking space
per 1,500 square feet of rentable space leased hereunder.

           9. MISCELLANEOUS. Except as amended herein, the Lease shall remain in
full force and effect. Defined terms in the Lease shall have the same meaning in
this Twelfth Amendment unless otherwise defined herein. This Twelfth Amendment
constitutes the entire agreement between the parties with respect to the subject
matter hereof. This Twelfth Amendment shall become binding upon Landlord and
Tenant only when fully executed by Landlord and Tenant.

           IN WITNESS WHEREOF, the parties have executed this Twelfth Amendment
to Lease as of the 26th day of November, 1996.


LANDLORD:                                   TENANT:

TODA DEVELOPMENT, INC.,                     MACROMEDIA, INC.,        
a California corporation                    a Delaware corporation   


By:  /s/ Shoichi Tozaki                     By: /s/ Richard B. Wood  
     ----------------------------               -------------------------------
      Its: President                              Its: V.P. Operations & CFO 



                                       72

<PAGE>   5
                          THIRTEENTH AMENDMENT TO LEASE

           THIS THIRTEENTH AMENDMENT TO LEASE (the "Amendment") is made and
entered into as of the date below written by and between TODA DEVELOPMENT, INC.,
a California corporation ("Landlord"), and MACROMEDIA, INC., a Delaware
corporation ("Tenant").


RECITALS

           A. Landlord and Tenant are parties to that certain lease dated June
27, 1991 for certain premises on the third floor of the building commonly known
as 600 Townsend Street, San Francisco, California, as amended by that certain
First Amendment to Lease dated May 4, 1992, the Second Amendment to Lease dated
August 9, 1994, the Third Amendment to Lease dated November 7, 1994, the Fourth
Amendment to Lease dated April 6, 1995, the Fifth Amendment to Lease dated
August 31, 1995, the Sixth Amendment to Lease dated October 31, 1995, the
Seventh Amendment to Lease dated December 15, 1995, the Eighth Amendment to
Lease dated January 25, 1996, the Ninth Amendment to Lease dated February 21,
1996, the Tenth Amendment to Lease dated April 30, 1996, the Eleventh Amendment
to Lease dated June 13, 1996, and the Twelfth Amendment to Lease dated November
26, 1996 (collectively, the "Lease"). Tenant's predecessor-in-interest under the
Lease was Macromind, Inc.

           B.   Landlord and Tenant desire to amend the Lease as set
forth below.


AGREEMENT

           Landlord and Tenant hereby agree as follows:

            1. ADDITIONAL PREMISES. Commencing as of April 1, 1997 (the
"Additional Premises Rental Commencement Date") the Premises shall include that
portion of the first floor of the Building comprising approximately 1,536
rentable square feet as shown on EXHIBIT A attached hereto (the "Additional
Premises"). The total rentable square footage of the Premises, including the
Additional Premises, shall be approximately 118,791 as shown on EXHIBIT B.

            2. DELIVERY OF ADDITIONAL PREMISES. Landlord shall deliver
possession of the Additional Premises as of April 1, 1997. If Landlord is unable
to deliver possession as of April 1, 1997, Landlord shall not be liable for any
damage caused for failing to deliver possession, and this Amendment shall not be
void or voidable. The 



                                       73
<PAGE>   6

Additional Premises Rental Commencement Date shall be delayed until Landlord
delivers possession of such space to Tenant. In the event that the Additional
Premises are delivered on other than April 1, 1997, Landlord and Tenant shall
execute a letter confirming the delivery date.

                RENTAL.  Commencing upon the Additional Premises Rental
Commencement Date, monthly Base Rental under the Lease shall be as
follows:

<TABLE>
<CAPTION>
             Period                        Rental  
             ------                        ------  
         <S>                           <C>
         4/1/97 -  8/31/97             $ 181,750.23
         9/1/97 - 12/31/01             $ 193,629.33
         1/1/02 - 12/31/03             $ 213,823.80
         1/1/04 - 12/31/05             $ 231,642.45
</TABLE>

           4. ADDITIONAL TENANT IMPROVEMENT ALLOWANCE. Landlord shall provide
Tenant with an additional Tenant Improvement Allowance in the amount of
$46,080.00 for the Additional Premises. Said allowance shall be paid and used
for the Additional Premises in accordance with paragraph 8 and Rider 5.C of the
Lease. Tenant may use its own contractor and architect (both subject to
Landlord's reasonable approval) for tenant improvement work in the Additional
Premises. All costs of design and construction shall be included within the
above Allowance.

            4. TENANT'S PARTICIPATION. Commencing as of the Additional Premises
Rental Commencement Date, Tenant's Participation for purposes of paragraph 6
shall be determined by using a numerator of 118,791 rentable square feet. The
base year shall be 1997 for the Additional Rental payable by Tenant with respect
to the Additional Premises.

            5. CONDITION OF ADDITIONAL PREMISES; IMPROVEMENTS. Tenant accepts
the Additional Premises in their "as is" condition. Tenant shall be responsible
for all demolition of and improvements to such premises and shall comply with
the terms of the Lease with respect to all work undertaken by Tenant, including,
without limitation, paragraphs 8 and 9 thereof.

            6. UTILITIES. Paragraph 4 of the Lease shall apply with respect to
utilities for the Additional Premises.

            7. SECURITY DEPOSIT. The Security Deposit shall be increased by
$2,995.20 which sum shall be paid by Tenant upon execution of this Thirteenth
Amendment and held in accordance with paragraph 5 of the Lease.

            8. PARKING. Upon delivery of the Additional Premises, Tenant shall
have the right to one (1) additional parking spaces in the Building Garage for a
total of 76 spaces. The initial charge shall be $88 per month per space for the
additional stall for the 



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<PAGE>   7

calendar year 1997. The charge shall increase 5% over the rate then in effect on
each anniversary of the Additional Premises Rental Commencement Date during the
initial term of the Lease. The charge during the option period shall be the Fair
Market Value. Notwithstanding the foregoing, if the garage becomes full Tenant
shall be entitled only to one parking space per 1,500 square feet of rentable
space leased hereunder.

            9. CONDITION PRECEDENT. The parties acknowledge that another tenant
has a right of first refusal with respect to the Additional Premises. Landlord
shall have the right to terminate this Amendment at any time prior to April 1,
1997 in the event that such tenant does not waive its right of first refusal. If
Landlord notifies Tenant that it has terminated this Amendment pursuant to this
paragraph 10, this Amendment shall be null and void and the parties shall have
no liability of any nature to each other with respect to this Amendment except
that Landlord shall return the security deposit paid by Tenant in accordance
with paragraph 8 above.

            10. WAIVER OF RIGHT OF FIRST REFUSAL. Tenant hereby waives the right
of first refusal with respect to the premises identified on EXHIBIT C.

            11. MISCELLANEOUS. Except as amended herein, the Lease shall remain
in full force and effect. Defined terms in the Lease shall have the same meaning
in this Thirteenth Amendment unless otherwise defined herein. This Thirteenth
Amendment constitutes the entire agreement between the parties with respect to
the subject matter hereof. This Thirteenth Amendment shall become binding upon
Landlord and Tenant only when fully executed by Landlord and Tenant.

            IN WITNESS WHEREOF, the parties have executed this Thirteenth
Amendment to Lease as of the 25th day of February, 1997.

LANDLORD:                                 TENANT:                      

TODA DEVELOPMENT, INC.,                   MACROMEDIA, INC.,            
a California corporation                  a Delaware corporation       


By:  /s/ Shoichi Tozaki                   By: /s/ John C. Parsons, Jr. 
     ------------------------------           ----------------------------------
      Its: President                            Its: CFO               
                                          


                                       75
<PAGE>   8

                          FOURTEENTH AMENDMENT TO LEASE

           THIS FOURTEENTH AMENDMENT TO LEASE (the "Amendment") is made and
entered into as of the date below written by and between TODA DEVELOPMENT, INC.,
a California corporation ("Landlord"), and MACROMEDIA, INC., a Delaware
corporation ("Tenant").

RECITALS

           A. Landlord and Tenant are parties to that certain lease dated June
27, 1991 for certain premises on the third floor of the building commonly known
as 600 Townsend Street, San Francisco, California, as amended by that certain
First Amendment to Lease dated May 4, 1992, the Second Amendment to Lease dated
August 9, 1994, the Third Amendment to Lease dated November 7, 1994, the Fourth
Amendment to Lease dated April 6, 1995, the Fifth Amendment to Lease dated
August 31, 1995, the Sixth Amendment to Lease dated October 31, 1995, the
Seventh Amendment to Lease dated December 15, 1995, the Eighth Amendment to
Lease dated January 25, 1996, the Ninth Amendment to Lease dated February 21,
1996, the Tenth Amendment to Lease dated April 30, 1996, the Eleventh Amendment
to Lease dated June 13, 1996, the Twelfth Amendment to Lease dated November 26,
1996, and the Thirteenth Amendment to Lease dated February 25, 1997
(collectively, the "Lease"). Tenant's predecessor-in-interest under the Lease
was Macromind, Inc.

           B.   Landlord and Tenant desire to amend the Lease as set
forth below.

AGREEMENT

           Landlord and Tenant hereby agree as follows:

           1. ADDITIONAL PREMISES. Commencing as of February 1, 1997 (the
"Additional Premises Delivery Date") the Premises shall include that portion of
the fourth floor of the Building comprising approximately 7,705 rentable square
feet as shown on EXHIBIT A attached hereto (the "Additional Premises"). The
total rentable square footage



                                       76
<PAGE>   9
of the Premises, including the Additional Premises, shall be approximately
126,496 as shown on EXHIBIT B.

           2. DELIVERY OF ADDITIONAL PREMISES. Landlord shall deliver possession
of the Additional Premises as of February 1, 1997. If Landlord is unable to
deliver possession as of February 1, 1997, Landlord shall not be liable for any
damage caused for failing to deliver possession, and this Amendment shall not be
void or voidable. The Additional Premises Delivery Date shall be delayed until
Landlord delivers possession of such space to Tenant. In the event that the
Additional Premises are delivered on other than February 1, 1997, Landlord and
Tenant shall execute a letter confirming the Additional Premises Delivery Date
and the Additional Premises Rental Commencement Date, which shall be delayed by
the same number of days as the Additional Premises Delivery Date.

           3. RENTAL. Commencing April 1, 1997 ("Additional Premises Rental
Commencement Date"), monthly Base Rental under the Lease shall be as follows:

<TABLE>
<CAPTION>
             Period                              Rental   
             ------                              ------   
         <S>                                 <C>
         4/1/97 -  8/31/97                   $ 193,538.88 
         9/1/97 - 12/31/01                   $ 206,188.48 
         1/1/02 - 12/31/03                   $ 227,692.80 
         1/1/04 - 12/31/05                   $ 246,667.20 
</TABLE>

           4. ADDITIONAL TENANT IMPROVEMENT ALLOWANCE. Landlord shall provide
Tenant with an additional Tenant Improvement Allowance in the amount of $77,050
for the Additional Premises. Said allowance shall be paid and used for the
Additional Premises in accordance with paragraph 8 and Rider 5.C of the Lease.
Tenant may use its own contractor and architect (both subject to Landlord's
reasonable approval) for tenant improvement work in the Additional Premises. All
costs of design and construction shall be included within the above Allowance.

           4. TENANT'S PARTICIPATION. Commencing as of the Additional Premises
Rental Commencement Date, Tenant's Participation for purposes of paragraph 6
shall be determined by using a numerator of 126,496 rentable square feet. The
base year shall be 1997 for the Additional Rental payable by Tenant with respect
to the Additional Premises.

           5. CONDITION OF ADDITIONAL PREMISES; IMPROVEMENTS. Tenant accepts the
Additional Premises in their "as is" condition. Tenant 



                                       77
<PAGE>   10

shall be responsible for all demolition of and improvements to such premises and
shall comply with the terms of the Lease with respect to all work undertaken by
Tenant, including, without limitation, paragraphs 8 and 9 thereof.

           6. UTILITIES. Paragraph 4 of the Lease shall apply with respect to
utilities for the Additional Premises.

           7. SECURITY DEPOSIT. The Security Deposit shall be increased by
$15,024.75 which sum shall be paid by Tenant upon execution of this Fourteenth
Amendment and held in accordance with paragraph 5 of the Lease.

           8. PARKING. Upon delivery of the Additional Premises, Tenant shall
have the right to a total of 76 parking spaces in the Building Garage.
Notwithstanding any other provision of this Lease to the contrary, the charge
for the parking spaces shall be $85.45 per month per space for the calendar year
1997. The charge shall increase 5% over the rate then in effect on each January
1 during the initial term of the Lease. The charge during the option period
shall be the Fair Market Value.

           9. MISCELLANEOUS. Except as amended herein, the Lease shall remain in
full force and effect. Defined terms in the Lease shall have the same meaning in
this Fourteenth Amendment unless otherwise defined herein. This Fourteenth
Amendment constitutes the entire agreement between the parties with respect to
the subject matter hereof. This Fourteenth Amendment shall become binding upon
Landlord and Tenant only when fully executed by Landlord and Tenant.

           IN WITNESS WHEREOF, the parties have executed this Fourteenth
Amendment to Lease as of the 25th day of February, 1997.


LANDLORD:                               TENANT:                  

TODA DEVELOPMENT, INC.,                 MACROMEDIA, INC.,        
a California corporation                a Delaware corporation   


By:  /s/ Shoichi Tozaki                 By: /s/ John C. Parsons, Jr.     
     ---------------------------            ------------------------------------
      Its: President                          Its:  CFO                  



                                       78