<PAGE>

                                                                   EXHIBIT 10.19

HAND DELIVERED

July 8, 1997

Joseph W. Seebach
8 Country Squire Drive
Norfolk, MA 02056


Dear Joe:


It is my sincere pleasure to offer you the position of Senior Vice President,
Software Products Group at OneWave, Inc.   The terms of our offer are as
follows:
1.   START DATE.  Your employment by the Company will start on July 9, 1997 (the
     "Start Date").

2.   SALARY.  Your starting salary will be paid based on a rate of $150,000 per
     year, payable twice each month in accordance with OneWave's standard
     payroll practices.  Your salary may be reviewed by the Company on an annual
     basis.

3.   CASH BONUS.  During the first two years of your employment, you will be
     eligible for cash bonuses with respect to successive complete calendar
     quarters ("Quarters"), as follows:

     a)   Each bonus is paid only if the Company reports earnings per share
          (EPS) in its periodic reports as filed with the SEC for any given
          Quarter of $ .25 per share or greater (the "Target EPS").
     b)   For each quarter during which the Target EPS is met, you will be paid
          a bonus (an "EPS Bonus") in the amount of $37,500 multiplied by the
          number of entire Quarters during which you were employed by the
          Company (including the partial Quarter ending September 30, 1997),
          minus the amount of any EPS Bonus(es) previously paid.  For example:

<TABLE>
<CAPTION>
          Q1        Q2        Q3        Q4        Q5        Q6        Q7        Q8
<S>       <C>       <C>       <C>       <C>       <C>       <C>       <C>       <C>
EPS:      .10       .20       .30       .20       .25       .10       .10       .10
Bonus:    $0        $0        $112.5k   $0        $75k      $0        $0        $0
</TABLE>

     c)   The final period for which you are eligible under this bonus plan is
          the Quarter ending June 30, 1999; the aggregate amount of these
          bonuses shall not exceed $300,000.  For subsequent periods during
          which you are employed, the Company will implement performance
          measures providing for incentive cash compensation targeted at a
          minimum of $150,000 per year.  You must be employed at the end of the
          Quarter to receive a bonus with respect to that quarter.

     d)   This bonus is not guaranteed; if the Target EPS is not met, the bonus
          will not be paid.

     e)   Bonuses earned will be paid within 60 days from the end of the Quarter
          with respect to which the Target EPS was met.

     f)   For purposes of this bonus plan, EPS may be adjusted by the Company in
          its discretion in the event that (i) there are one-time or
          extraordinary expenses, revenues or other items, or (ii) there
          is any stock split, recapitalization, merger, stock offering and the
          like, or (iii) the Company is no longer subject to SEC reporting
          requirements.


<PAGE>

                              ONE WAVE CONFIDENTIAL           Mr. Joseph Seebach
                                                                    July 8, 1997
                                                                          Page 2

4.   NON-QUALIFIED STOCK OPTION.  You will be granted a fully vested
     Non-Qualified Stock Option ("NQSO") to purchase 100,000 shares of Stock
     (the "NQSO Shares") with an exercise price equal to the last reported sale
     price on the third NASDAQ trading day following announcement of Q2 '97
     results (the "Initial Price"); you agree to exercise such vested option in
     full within twenty business days from the Grant Date, and to purchase the
     NQSO Shares.  

     a)   The Company shall have the right and option, but not the obligation,
          upon the termination of your employment by the Company, to re-purchase
          the NQSO Shares from you for a per share price equal to Initial Price.
          This re-purchase option may be exercised any time within 90 days from
          your termination.

     b)   OneWave's re-purchase option applies to the full amount of the NQSO
          Shares, reduced by 6,250 shares on September 30, 1997, and reduced by
          another 6,250 shares on the first day following each full Quarter that
          you are employed by OneWave.

     c)   You agree that all NQSO Shares which are subject to OneWave's
          re-purchase option are restricted, and may not be assigned, sold or
          transferred to any person for any reason, except to family members for
          estate planning purposes.  The NQSO shares will be represented by 16
          certificates for 6,250 shares each, to be held by the Company and
          delivered to you as and when OneWave's re-purchase option lapses.

     d)   You will be solely responsible for obtaining your desired tax
          treatment in connection with such option and shares, including without
          limitation filing an "83(b) Election" with the IRS within 30 days from
          the date of exercise.

5.   INCENTIVE STOCK OPTION.  You will be granted an Incentive Stock Option
     ("ISO") for 250,000 shares, subject to annual ISO limitations imposed under
     the Internal Revenue Code.  Any option which cannot qualify as an ISO will
     be issued as a NQSO.

     a)   This ISO shall vest in 16 equal quarterly installments commencing with
          your date of employment.

     b)   This ISO shall be granted on the Grant Date, having an exercise price
          equal to Initial Price.

6.   RELOCATION.  The Company will pay you the lump sum of $50,000 in order to
     defray your relocation expenses.  You are not required to account for your
     use of these funds.  In addition, OneWave will reimburse the reasonable
     airfare, lodging, meals and local travel expenses incurred by you and your
     immediate family in connection with up to three trips to the greater Boston
     area to locate suitable housing.  OneWave will  have no other obligation
     with respect to your relocation and associated costs and expenses.

7.   BENEFITS.  You will be eligible for all health insurance and other benefit
     programs as made available to other Company officers, including:
     contributory medical, dental, and life insurance,  health reimbursement, a
     paid vacation, and a 401(k) salary deferral program. Vacation time is
     accrued after your first month of employment, you will be entitled to three
     weeks for the first five years of employment, and four weeks for each year
     thereafter, with rates of accrual and use based on OneWave's policies. In
     addition, OneWave observes ten holidays per year.  You will travel in
     accordance with OneWave's policies, which have limitations on first class
     travel.


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                              ONE WAVE CONFIDENTIAL           Mr. Joseph Seebach
                                                                    July 8, 1997
                                                                          Page 3

8.   TERMINATION OF EMPLOYMENT. 

     a)   CHANGE IN CONTROL. In the event that the Company engages in or becomes
          subject to a "Business Combination", as defined in Section 203 of the
          Delaware General Corporation Law, and you are terminated within the
          succeeding 18 months for any reason other than gross misconduct,
          violation of law or unethical conduct, then:

          i)   you will be entitled to receive continuation of your then-current
               base salary for one (1) year following termination;

          ii)  you will be entitled to receive cash bonuses for the then-current
               and three Quarters following termination, for any such Quarter(s)
               where the Target EPS is met;

          iii) all unvested stock options will accelerate and become immediately
               exercisable, but must be exercised within 90 days from
               termination; 

          iv)  the number of NQSO Shares to which the Company's re-purchase
               option apply shall immediately be reduced to only such number of
               shares as would have been covered at the expiration of one (1)
               year following your termination; and

          v)   the Company will reimburse you for up to $35,000 of your actual
               and reasonable relocation costs for your return to California.

     b)   TERMINATION WITHOUT CAUSE.  In the event that, within 24 months
          following your Start Date, your employment is terminated by OneWave
          for reasons other than demonstrable lack of performance, gross
          misconduct, violation of law or unethical conduct (and provided that
          you are not entitled to consideration under Section 10(a) above),
          then: 

          i)   you will be entitled to receive continuation of your then-current
               base salary for the "Roll-off Period", defined as the period
               ending on the later of the following:  (A) six months from
               termination, or (B) 24 months from your Start Date; 

          ii)  you will be entitled to receive cash bonuses during the Roll-off
               Period for any Quarter(s) ending in the Roll-off Period for which
               the Target EPS is met, 

          iii) your stock options will continue to vest during the Roll-Off
               Period in accordance with their terms, but must be exercised
               within 90 days from the end of the Roll-off Period; 

          iv)  the number of NQSO Shares to which the Company's re-purchase
               option apply shall continue to be reduced during the Roll-off
               Period in accordance with its terms; and 

          v)   the Company will reimburse you for up to $35,000 of your actual
               and reasonable relocation costs for your return to California.

     c)   NO EMPLOYMENT CONTRACT.  Except to the extent specifically provided
          above, the Company will have no obligation or liability to you as a
          result of the termination of your employment by either party for any
          reason.  This is not a contract of employment, and you specifically
          acknowledge that you will be an employee-at-will.

On your first day of employment, you will be required to execute OneWave's
standard Employee Agreement (copy enclosed), and to provide satisfactory proof
of eligibility for employment in the United States.  In this regard, please fill
out Part 1 of the attached INS Form I-9, and bring with you the documentation
required by Part 2.


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                              ONE WAVE CONFIDENTIAL           Mr. Joseph Seebach
                                                                    July 8, 1997
                                                                          Page 4


Joe, I know that we have been in discussions since the first week of June, and
that this has taken a very long time to work out.  I appreciate your patience,
and sincerely expect that your commitment will be rewarded.

Please indicate your agreement to the terms of this Offer by countersigning
where indicated below, and then return a fully executed copy to me at your
earliest convenience. We will then prepare definitive agreements regarding your
compensation.

If you any questions or concerns, please do not hesitate to contact me.

I look forward to having you on board at OneWave.


Sincerely,

/s/ Kevin Azzouz

Kevin Azzouz
President and CEO

                              AGREED:

                              /s/ Joseph W. Seebach
                              ------------------------------------
                              Mr. Joseph W. Seebach

                              Date:  7/16/97
                                   -------------------------------