<PAGE>
                                                                   EXHIBIT 10.22

                                F5 NETWORKS, INC.

                       NONQUALIFIED STOCK OPTION AGREEMENT

        THIS NONQUALIFIED STOCK OPTION AGREEMENT (the "Agreement") is made and
entered into as of May 29, 2001 (the "Grant Date") between F5 Networks, Inc., a
Washington corporation (the "Company") and Steve Coburn ("Holder").

        THE PARTIES AGREE AS FOLLOWS:

        1. GRANT OF OPTION; GRANT DATE. The Company hereby grants to Holder, the
right (the "Option") to purchase up to 200,000 shares of the Company's Common
Stock (the "Option Shares") at a price per share of $12.72 (the "Exercise
Price"), on the terms and conditions set forth in this Agreement. This Option is
not intended to qualify as an incentive stock option for purposes of Section 422
of the Code. The number and kind of Option Shares and the Exercise Price may be
adjusted in certain circumstances in accordance with the provisions of Section 9
below.

        2. DEFINITIONS. For purposes of this Agreement, the following terms
shall be defined as set forth below:

            2.1 Affiliate. "Affiliate" means any parent corporation or
subsidiary corporation of the Company, whether now or hereafter existing.

            2.2 Board. "Board" means the Board of Directors of the Company.

            2.3 Code. "Code" means the Internal Revenue Code of 1986, as
amended.

            2.4 Common Stock. "Common Stock" means the common stock of the
Company.

            2.5 Continuous Service. "Continuous Service" means that Holder's
service with the Company or an Affiliate, whether as an employee or consultant,
is not interrupted or terminated. Holder's Continuous Service shall not be
deemed to have terminated merely because of a change in the capacity in which
Holder renders service to the Company or an Affiliate as an employee or
consultant or a change in the entity for which Holder renders such service,
provided that there is no interruption or termination of Holder's Continuous
Service. For example, a change in status from an employee of the Company to a
consultant of an Affiliate will not constitute an interruption of Continuous
Service. The Board, in its sole discretion, may determine whether Continuous
Service shall be considered interrupted in the case of any leave of absence
approved by the Board, including sick leave, military leave or any other
personal leave.

            2.6 Disability. "Disability" means the permanent and total
disability of Holder within the meaning of Section 22(e)(3) of the Code.

            2.7 Expiration Date. "Expiration Date" means May 29, 2011.



<PAGE>


            2.8 Fair Market Value. "Fair Market Value" means, as of any date,
the value of the Common Stock. If the Common Stock is listed on any established
stock exchange or traded on the NASDAQ National Market or the NASDAQ Small Cap
Market, the Fair Market Value of a share of Common Stock shall be the closing
sales price for such stock (or the closing bid, if no sales were reported) as
quoted on such exchange or market (or the exchange or market with the greatest
volume of trading in the Common Stock) on the day of determination or, if the
day of determination is not a market trading day, then on the last market
trading day prior to the day of determination, as reported in The Wall Street
Journal or such other source as the Board deems reliable. In the absence of such
markets for the Common Stock, the Fair Market Value shall be determined in good
faith by the Board.

            2.9 Securities Act. "Securities Act" means the Securities Act of
1933, as amended.

            2.10 Vesting Commencement Date. "Vesting Commencement Date" shall
mean Holder's first day of continuous service with the Company.

        3. VESTING. Subject to the limitations contained herein, the Option will
vest and become exercisable with respect to 25% of the Option Shares on the
first anniversary of the Vesting Commencement Date and with respect to the
remaining Option Shares in equal monthly installments over the three years
following the Vesting Commencement Date; provided that vesting will cease upon
the termination of Holder's Continuous Service.

        4. METHOD OF PAYMENT OF THE EXERCISE PRICE. Payment of the Exercise
Price is due in full upon exercise of all or any part of the Option. Holder may
elect to make payment of the Exercise Price in cash or by check or one or more
of the following if the Company, in its sole discretion at the time the Option
is exercised, is then offering such alternatives:

            (a) Provided that at the time of exercise the Common Stock is
publicly traded and quoted regularly in The Wall Street Journal, then pursuant
to a program developed under Regulation T as promulgated by the Federal Reserve
Board which, prior to the issuance of Common Stock, results in either the
receipt of cash (or check) by the Company or the receipt of irrevocable
instructions to pay the aggregate exercise price to the Company from the sales
proceeds (a "cashless exercise").

            (b) Provided that at the time of exercise the Common Stock is
publicly traded and quoted regularly in The Wall Street Journal, then by
delivery of already-owned shares of Common Stock (valued at their Fair Market
Value on the date of exercise) if (i) either Holder has held the already-owned
shares for the period required to avoid a charge to the Company's reported
earnings (generally six months) or Holder did not acquire the already-owned
shares, directly or indirectly from the Company and (ii) Holder owns the
already-owned shares free and clear of any liens, claims, encumbrances or
security interests. "Delivery" for these purposes, in the sole discretion of the
Company at the time the Option is exercised, shall include delivery to the
Company of Holder's attestation of ownership of such shares of Common Stock in a
form approved by the Company. Notwithstanding the foregoing, the Option may not
be exercised by tender to the Company of Common Stock to the extent such tender
would constitute a violation


                                       2
<PAGE>

of the provisions of any law, regulation or agreement restricting the redemption
of the Company's stock.

            (c) Provided there has been a change in control described in Section
9(c) and the surviving corporation or acquiring corporation refuses to assume
the Option or to substitute a similar option for the Option, then by authorizing
the Company to withhold shares from the shares of the Common Stock otherwise
issuable to Holder as a result of the exercise of the Option. Notwithstanding
the foregoing, the Option may not be exercised by withholding shares of Common
Stock to the extent such withholding would constitute a violation of the
provisions of any law, regulation or agreement restricting the redemption of the
Company's stock.

        5. WHOLE SHARES. The Option may only be exercised for whole shares.

        6. SECURITIES LAW COMPLIANCE. Notwithstanding anything to the contrary
contained herein, the Option may not be exercised unless the shares issuable
upon exercise of the Option are then registered under the Securities Act or, if
such shares are not then so registered, the Company has determined that such
exercise and issuance would be exempt from the registration requirements of the
Securities Act. The exercise of the Option must also comply with other
applicable laws and regulations governing the Option, and the Option may not be
exercised if the Company determines that the exercise would not be in material
compliance with such laws and regulations.

        7. TERM. The term of the Option commences on the Grant Date and expires
upon the EARLIEST of the following:

            (a) three (3) months after the termination of Holder's Continuous
Service for any reason other than death or Disability, provided that if during
any part of such three-month period the Option is not exercisable solely because
of the condition set forth in Section 6, the Option shall not expire until the
earlier of the Expiration Date or until it shall have been exercisable for an
aggregate period of three (3) months after the termination of Holder's
Continuous Service;

            (b) twelve (12) months after the termination of Holder's Continuous
Service due to Disability;

            (c) eighteen (18) months after Holder's death if Holder dies either
during Holder's Continuous Service or within three (3) months after Holder's
Continuous Service terminates for reason other than Cause;

            (d) the Expiration Date; or

            (e) the tenth (10th) anniversary of the Grant Date.


                                       3
<PAGE>

        8. EXERCISE.

            (a) The vested portion of the Option may be exercised during its
term by delivering a Notice of Exercise in the form attached hereto as Exhibit
A, together with the Exercise Price (payable in the manner set forth in Section
4) to the Secretary of the Company, or to such other person as the Company may
designate, during regular business hours, together with such additional
documents as the Company may then require.

            (b) By exercising the Option, Holder agrees that, as a condition to
any exercise of the Option, the Company may require Holder to enter an
arrangement providing for the payment by Holder to the Company of any tax
withholding obligation of the Company arising by reason of (1) the exercise of
the Option or (2) the disposition of shares acquired upon such exercise.

        9. ADJUSTMENTS UPON CHANGES IN STOCK.

            (a) Capitalization Adjustments. If any change is made in the Common
Stock without the receipt of consideration by the Company (through merger,
consolidation, reorganization, recapitalization, reincorporation, stock
dividend, dividend in property other than cash, stock split, liquidating
dividend, combination of shares, exchange of shares, change in corporate
structure or other transaction not involving the receipt of consideration by the
Company), the number of Option Shares and the Exercise Price will be
appropriately adjusted by the Board, whose determination shall be final, binding
and conclusive. (The conversion of any convertible securities of the Company
shall not be treated as a transaction "without receipt of consideration" by the
Company.)

            (b) Change in Control--Dissolution or Liquidation. In the event of a
dissolution or liquidation of the Company, the Option shall be terminated if not
exercised (if applicable) prior to such event.

            (c) Change in Control--Asset Sale, Merger, Consolidation or Reverse
Merger.

                (i) The Option will immediately vest 100% in the event of a
change in control of the Company consisting of: (1) a sale of substantially all
of the assets of the Company, (2) a merger or consolidation in which the Company
is not the surviving corporation or (3) a reverse merger in which the Company is
the surviving corporation but the shares of Common Stock outstanding immediately
preceding the merger are converted by virtue of the merger into other property,
whether in the form of securities, cash or otherwise. If applicable, the time
during which the Option may be exercised shall also be accelerated in full. The
Option shall terminate if not exercised (if applicable) at or prior to such
event, and any surviving corporation or acquiring corporation shall assume the
remaining unvested portion of the Option or shall substitute a similar Option.


                                       4
<PAGE>

                (ii) For purposes of subsection 9(c) the Option shall be deemed
assumed if, following the change in control, the Option confers the right to
purchase, in accordance with its terms and conditions, for each share of Common
Stock subject to the Option immediately prior to the change in control, the
consideration (whether stock, cash or other securities or property) to which a
holder of a share of Common Stock on the effective date of the change in control
was entitled.

        10. TRANSFERABILITY. The Option is not transferable, except by will or
by the laws of descent and distribution, and is exercisable during Holder's life
only by Holder. Notwithstanding the foregoing, by delivering written notice to
the Company, in a form satisfactory to the Company, Holder may designate a third
party who, in the event of Holder's death, shall thereafter be entitled to
exercise the Option.

        11. NOT A SERVICE CONTRACT. This Agreement is not an employment or
service contract, and nothing in this Agreement shall be deemed to create in any
way whatsoever any obligation on Holder's part to continue in the employ of the
Company, or of the Company to continue Holder's employment. In addition, nothing
in this Agreement shall obligate the Company, its shareholders, Board, officers
or employees to continue any relationship that Holder might have as a director
or consultant for the Company.

        12. WITHHOLDING OBLIGATIONS.

            (a) At the time the Option is exercised, in whole or in part, or at
any time thereafter as requested by the Company, Holder hereby authorizes
withholding from payroll and any other amounts payable to Holder, and otherwise
agrees to make adequate provision for (including by means of a "cashless
exercise" pursuant to a program developed under Regulation T as promulgated by
the Federal Reserve Board to the extent permitted by the Company), any sums
required to satisfy the federal, state, local and foreign tax withholding
obligations of the Company, which arise in connection with the Option.

            (b) The Option is not exercisable unless the tax withholding
obligations of the Company are satisfied. Accordingly, Holder may not be able to
exercise the Option when desired even though the Option is vested.

        13. NO RIGHTS AS A SHAREHOLDER. The Option shall not entitle the Holder
to any cash dividend, voting or other right of a shareholder unless and until
the date of issuance of the shares that are the subject of the Option.

        14. PROFESSIONAL ADVICE. The acceptance and exercise of the Option and
the sale of Option Shares has consequences under federal and state tax and
securities laws which may vary depending upon the individual circumstances of
the Holder. Accordingly, Holder acknowledges that he has been advised to consult
his personal legal and tax advisor in connection with this Agreement and his
dealings with respect to the Option and the Option Shares. Holder further
acknowledges that the Company has made no warranties or representations to
Holder with respect to the income tax consequences of the grant and exercise of
the Option or the sale of the


                                       5
<PAGE>

Option Shares and Holder is in no manner relying on the Company or its
representatives for an assessment of such consequences.

        15. ASSIGNMENT; BINDING EFFECT. Subject to the limitations set forth in
this Agreement, this Agreement shall be binding upon and inure to the benefit of
the executors, administrators, heirs, legal representatives, and successors of
the parties hereto; provided, however, that Holder may not assign any of
Holder's rights under this Agreement.

        16. DAMAGES. Holder shall be liable to the Company for all costs and
damages, including incidental and consequential damages, resulting from a
disposition of Option Shares which is not in conformity with the provisions of
this Agreement.

        17. GOVERNING LAW. This Agreement shall be governed by, and construed in
accordance with, the laws of the State of Washington excluding those laws that
direct the application of the laws of another jurisdiction.

        18. NOTICES. All notices and other communications under this Agreement
shall be in writing. Unless and until Holder is notified in writing to the
contrary, all notices, communications, and documents directed to the Company and
related to the Agreement, if not delivered by hand, shall be mailed, addressed
as follows:

                      F5 Networks, Inc.
                      401 Elliott Ave West
                      Seattle, WA  98119

Unless and until the Company is notified in writing to the contrary, all
notices, communications, and documents intended for Holder and related to this
Agreement, if not delivered by hand, shall be mailed to Holder's last known
address as shown on the Company's books. Notices and communications shall be
mailed by first class mail, postage prepaid. All mailings and deliveries related
to this Agreement shall be deemed received when actually received, if by hand
delivery, and five (5) business days after mailing, if by mail.

        19. AMENDMENT OF THIS AGREEMENT. The Board at any time, and from time to
time, may amend the terms of this Agreement; provided, however, that the rights
under this Agreement shall not be impaired by any such amendment unless (i) the
Company requests the consent of the Holder and (ii) Holder consents in writing.


                                       6
<PAGE>

        IN WITNESS WHEREOF, the parties have executed this Option Agreement as
of the Effective Date.

                            F5 NETWORKS, INC.

                            By    /s/ Joann Reiter
                                  ----------------------------------------------
                            Title Vice President and General Counsel
                                  ----------------------------------------------

Holder hereby accepts and agrees to be bound by all of the terms and conditions
of this Agreement.

                            /s/ STEVEN B. COBURN
                            ----------------------------------------------------
                            Holder



                                       7
<PAGE>

                                    EXHIBIT A

                               NOTICE OF EXERCISE

                   (To be signed only upon exercise of Option)


To:     F5 Networks, Inc.
        401 Elliott Ave West
        Seattle, WA  98119


        The undersigned, the holder of an option to purchase shares of common
stock of F5 Networks, Inc. pursuant to an Option Agreement dated as of
__________ __, ____ (the "Option Agreement") hereby irrevocably elects to
exercise the purchase right represented by the Option Agreement for, and to
purchase under that Option Agreement, __________ shares of Common Stock and
herewith makes payment of $_____________ for those shares and payment of
$___________ for holder's share of withholding and employment taxes resulting
from such exercise. Holder hereby confirms the representations, warranties and
agreements set forth in the Option Agreement.

        DATED: __________________, ____.


                                            HOLDER:

                                            ------------------------------------




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

                                            ADDRESS:

                                            ------------------------------------

                                            ------------------------------------

                                            ------------------------------------