Promissory Note - Akamai Technologies Inc. and Paul Sagan


                                 PROMISSORY NOTE

                                                                    May 18, 1999
$500,000                                                   Boston, Massachusetts

         FOR VALUE RECEIVED, Paul Sagan (the 'Maker'), promises to pay to Akamai
Technologies, Inc. (the 'Company'), or order, at its offices or at such other
place as the holder of this Note may designate, the principal sum of $500,000,
together with interest on the unpaid principal balance of this Note from time to
time outstanding at the rate of 5.3% per year, compounded annually, until paid
in full. Principal and interest shall be paid in full on May 18, 2009; provided,
however, if the Maker sells any shares of the Company, he shall make a
prepayment on this Note equal to the proceeds of such sale (net of taxes), such
payment applied first to accrued and unpaid interest and then to principal until
paid in full.

         Interest on this Note shall be computed on the basis of a year of 365
days for the actual number of days elapsed. All payments by the Maker under this
Note shall be in immediately available funds.

         This Note shall become immediately due and payable without notice
(except as provided in paragraph (1) below) or demand upon the occurrence at any
time of any of the following events of default (individually, 'an Event of
Default' and collectively, 'Events of Default'):

         (1)      default in the payment or performance of this or any other
                  liability or obligation of the Maker under a written contract
                  to the holder that is not cured within 30 days after written
                  notice of default thereof, including the payment when due of
                  any principal, premium or interest under this Note;

         (2)      the insolvency of the Maker, or the appointment of a receiver
                  or custodian for the Maker or any part of its property if such
                  appointment is not terminated or dismissed within thirty (30)
                  days;

         (3)      the institution against the Maker or any indorser or guarantor
                  of this Note of any proceedings under the United States
                  Bankruptcy Code or any other federal or state bankruptcy,
                  reorganization, receivership, insolvency or other similar law
                  affecting the rights of creditors generally, which proceeding
                  is not dismissed within thirty (30) days of filing; or

         (4)      the institution by the Maker or any indorser or guarantor of
                  this Note of any proceedings under the United States
                  Bankruptcy Code or any other federal or state bankruptcy,
                  reorganization, receivership, insolvency or other similar law
                  affecting the rights of creditors generally or the making by
                  the Maker or any indorser or guarantor of this Note of a
                  composition or an assignment or trust mortgage for the benefit
                  of creditors.

         Upon the occurrence of an Event of Default, the holder shall have then,
or at any time thereafter, all of the rights and remedies afforded by the
Uniform Commercial Code

as from time to time in effect in the Commonwealth of Massachusetts or afforded
by other applicable law.

         All payments by the Maker under this Note shall be made without set-off
or counterclaim and be free and clear and without any deduction or withholding
for any taxes or fees of any nature whatever, unless the obligation to make such
deduction or withholding is imposed by law. The Maker shall pay and save the
holder harmless from all liabilities with respect to or resulting from any delay
or omission to make any such deduction or withholding required by law.

         No reference in this Note to any guaranty or other document shall
impair the obligation of the Maker, which is absolute and unconditional, to pay
all amounts under this Note strictly in accordance with the terms of this Note.

         The Maker agrees to pay on demand all costs of collection, including
reasonable attorneys' fees, incurred by the holder in enforcing the obligations
of the Maker under this Note.

         No delay or omission on the part of the holder in exercising any right
under this Note shall operate as a waiver of such right or of any other right of
such holder, nor shall any delay, omission or waiver on any one occasion be
deemed a bar to or waiver of the same or any other right on any future occasion.
The Maker and every indorser or guarantor of this Note regardless of the time,
order or place of signing waives presentment, demand, protest and notices of
every kind and assents to any extension or postponement of the time of payment
or any other indulgence, to any substitution, exchange or release of collateral,
and to the addition or release of any other party or person primarily or
secondarily liable.

         This Note may be prepaid in whole or in part at any time or from time
to time. Any such prepayment shall be without premium or penalty.

         None of the terms or provisions of this Note may be excluded, modified
or amended except by a written instrument duly executed on behalf of the holder
expressly referring to this Note and setting forth the provision so excluded,
modified or amended.

         All rights and obligations hereunder shall be governed by the laws of
the Commonwealth of Massachusetts and this Note is executed as an instrument
under seal.

                                                            /s/ Paul Sagan
                                                            Paul Sagan

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