Document:

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                                                                   EXHIBIT 10.21

                               THIRD AMENDMENT TO
                             JOINT VENTURE AGREEMENT

This Third Amendment to the Joint Venture Agreement ("Third Amendment") is made
and entered into as of August 9, 2001 by and among Trans Cosmos, Inc., a
Japanese corporation ("TCI"), Primus Knowledge Solutions, Inc., a corporation
organized under the laws of the State of Washington, U.S.A. ("Primus"), and
Primus Knowledge Solutions KK Japan, a Primus/TCI joint venture company
organized under the laws of Japan as a kabushiki kaisha ("Primus KK").

                                   BACKGROUND

Primus and TCI established Primus KK under a Joint Venture Agreement ("JVA")
dated November 16, 1995. Primus, TCI and Primus KK subsequently amended the
terms and conditions of the JVA on September 25, 1997 (the "First Amendment")
and again on July 17, 2000 (the "Second Amendment").

Primus and TCI now wish to amend the JVA as follows:

                                    AMENDMENT

1. Statutory Auditor. Article 5 of the JVA is amended to provide that Primus KK
   -----------------
shall have one (1) statutory auditor as  mutually agreed by
Primus and TCI in writing and appointed by TCI in compliance with such
agreement.

2. Documentation and Procedures. Primus KK shall ensure that all necessary
   ----------------------------
Japanese governmental approvals and filings have been obtained and that the
proper corporate governance procedures have been followed in order to effectuate
this Third Amendment.

3. Effect of Amendment. All references to the subject matter of Article 5 of the
   -------------------
JVA in the First and Second Amendments shall be construed in a manner consistent
with Section 1 of this Third Amendment. Except as expressly amended by this
Third Amendment, and the First and Second Amendments, all other terms and
conditions of the JVA shall remain unaltered and in full force and effect.

4. Governing Language. This Third Amendment is executed in the English language
   ------------------
which version shall control for all purposes.

This Third Amendment shall take effect immediately on the date first set forth
above.

PRIMUS KNOWLEDGE SOLUTIONS, INC.               TRANS COSMOS, INC.

By: /s/ Michael A. Brochu                      By: /s/ Yasuki Matsumoto

Print: Michael A. Brochu                       Print: Yasuki Matsumoto

Title: President and CEO                       Title: Executive Vice President

PRIMUS KNOWLEDGE SOLUTIONS KK JAPAN

By: /s/ Masahiro Sasaki

Print: Masahiro Sasaki

Title: CEO & President<PAGE>

                                                                   EXHIBIT 10.22

                               FORTH AMENDMENT TO
                             JOINT VENTURE AGREEMENT

     Pursuant to Section 22 of the Joint Venture Agreement dated November 16,
1995 (the "JVA"), Primus Knowledge Solutions, Inc. ("Primus") and Trans Cosmos,
Inc. ("TCI") agree to amend the terms and conditions of their JVA with respect
to the formation and operation of their joint venture company, Primus Knowledge
Solutions, K.K. ("Primus KK"), effective this 7th day of November, 2001 (the
"Forth Amendment") as follows. Unless otherwise provided, capitalized terms used
in this Forth Amendment have the same meaning ascribed them in the JVA.

Section 1. Contract Term
           -------------

1.1  Article 10 Contract Term is amended in its entirety to provide as follows:
"Except as otherwise provided in Article 11 below, this Agreement shall continue
in effect unless earlier terminated (i) by mutual agreement; or (ii)
automatically upon the initial public offering of Primus KK resulting in the
registration for sale of the common stock of Primus KK (including stock held by
Primus and TCI subject to reasonable commercially standard lock up provisions)
on a recognized stock market."

Section 2. Cause for Termination of this Contract
           --------------------------------------

2.1  Article 11 Cause for Termination of this Contract, subsections (b) and (d)
are deleted in their entirety and all references to these subsections in the
text of the Agreement are removed.

Section 3.        Initial Public Offering
                  -----------------------

3.1  Primus and TCI will work in good faith and use commercially reasonable
     efforts to file an initial public offering for the sale of the common stock
     of Primus KK on a recognized stock market ("IPO") at a time when the Primus
     KK Board of Directors, under the counsel of an investment bank selected by
     the Primus KK Board of Directors, determine an IPO filing would be
     reasonable, but in any event prior to December 31, 2004.

               [Intentionally left blank--Signature page follows]

<PAGE>

All other terms and conditions of the JVA not modified by this Forth Amendment,
and the First, Second and Third Amendments remain in full force and effect. This
Forth Amendment is executed in the English language which version controls for
all purposes.

Primus Knowledge Solutions, Inc.                Primus Knowledge Solutions, K.K.

       /s/ Michael B. Brochu                           /s/ Masahiro Sasaki

Print: Michael A. Brochu                        Print: Masahiro Sasaki

Title: President and CEO                        Title: CEO and President

Date:  November 7, 2001                         Date:  November 7, 2001

Trans Cosmos, Inc.

       /s/ Yasuki Matsumoto

Print: Yasuki Matsumoto

Title: Executive Vice President

Date:  November 7, 2001<PAGE>

                                                                   EXHIBIT 10.23

November 7, 2001

Primus Knowledge Solutions, KK
Ebisu Prime Sq. Tower
1-1-39 Hiroo, Shibuya-ku
Tokyo, Japan 150

Re:    Addendum One to Amended and Restated Distribution Agreement
       -----------------------------------------------------------
       ("Agreement"), effective March 31, 2000, between Primus Knowledge
       -----------------------------------------------------------------
       Solutions, Inc. ("Primus") and Primus Knowledge Solutions, KK.
       --------------------------------------------------------------
       ("Distributor")
       ---------------

Dear Sasaki-san:

We have recently discussed a number of issues with respect to our Agreement.
This Addendum One will clarify and memorialize our agreement on these points.
Except as otherwise expressly defined in this Amendment, capitalized terms shall
have the meanings ascribed to them in the License Agreement.

Therefore, we hereby agree to amend our Agreement as follows:

1.   All references to KBI products are hereby deemed removed from the Agreement
     and Distributor shall not promote or distribute any KBI products under this
     Agreement.

2.   Footnote 1 to Table A shall be revised to read,

     Primus(R) eServer is formerly known as SolutionSeries(TM) Server,
     SolutionBuilder(R) and SolutionExplorer(R). In the event that Primus
     provides Distributor, any Subdistributor or any End User with
     Chili!Soft(TM) ASP software, Distributor shall ensure that such
     Chili!Soft(TM) ASP software is only used in connection with the Primus(R)
     eServer software and will pay Primus an additional US$1,000 Licensee Fee
     for each production copy of the Chili!Soft(TM) ASP software distributed to
     an End User. With respect to any End User who receives such Chili!Soft(TM)
     ASP software in connection with this Agreement and whose total initial
     acquisition equals or exceeds twenty-five (25) seats (license type
     regardless) of Primus eServer and/or Primus eSupport, Primus will waive the
     US$1,000 licensee fee with respect to one (1) production copy of
     Chili!Soft(TM) ASP software provided to such End User, providing that the
     End User is not charged a distribution fee, license fee or the like for the
     one (1) free production copy of Chili!Soft(TM) ASP software. The foregoing
     provision of one (1) production copy of Chili!Soft(TM) ASP software shall
     not apply to any current End Users or any End Users who initially acquire
     less than 25 seats of Primus eServer and/or Primus eSupport. Primus will
     notify Distributor of any change in the pricing of ChiliSoft ASP software
     and such price changes will be effective when the same are effective for
     Primus with respect to its use of ChiliSoft ASP software.

                                       1

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3.   The "Support and Maintenance Fees" for Primus(R) eServer and Primus(R)
     eSupport set forth in Table B is hereby revised from "50%" to "53%".

4.   The reference to "Seagate Crystal Info v.6" in Table A shall be revised to
     read, "Seagate Crystal Info v.7.0 and v.7.5".

5.   Note 3 to Table A shall be replaced in its entirety with the following:

     End User's rights are limited to "Client licenses" (no OLAP or
     Report/Query) for use only in conjunction with the Primus software licensed
     by the End User and subject to the licensing and other restrictions set
     forth in the Seagate Crystal Info shrink-wrap agreement provided with the
     Seagate Crystal Info software. In no event shall Distributor or any
     Sub-Distributor distribute any Seagate Crystal Info software in any form
     other than the unopened shrink-wrapped packages in which such software is
     initially shipped.

6.   The Price Per Unit of Seagate Crystal Info Set under Table B shall be
     revised to read, "$1,500 per Seagate Crystal Info Set" and the Support and
     Maintenance Fees of "18%" shall be replaced by "See Note 4".

7.   Note 3 to Table B shall be replaced in its entirety with the following:

     Seagate Crystal Info Set refers to a set of five (5) licenses of Seagate
     Crystal Info. V.7.0 or v.7.5 software. Table B notwithstanding, in the
     event that Distributor enters into a License Agreement with an End User for
     a total initial acquisition of twenty-five (25) seats (license type
     regardless) or more of Primus eServer and/or Primus eSupport, Primus will
     waive the US$1,500 licensee fee with respect to the one (1) Seagate Crystal
     Info Set provided by Distributor to such End User, providing the End User
     is not charged a distribution fee, license fee or the like for the free
     single Seagate Crystal Info Set. The foregoing provision of a free Seagate
     Crystal Info Set shall not apply to any current End Users or any End Users
     who initially acquire less than 25 seats of Primus eServer and/or Primus
     eSupport. Primus will notify Distributor of any change in the pricing of
     Seagate Crystal software and such price changes will be effective when the
     same are effective for Primus with respect to its use of Seagate Crystal
     software.

8.   A new Note 4 to Table B shall be added as follows:

     Primus' support obligations relating to the Seagate Crystal Info v.7.0 and
     v.7.5 shall be limited only to Secondline Support for the standard reports
     that are provided by Primus as a part of such software and for only as long
     as Primus is generally making support available for such Seagate version in
     connection with the English language version of the applicable Primus
     Product. No upgrades or updates are provided to Seagate Crystal products.

9.   Section 1.2 is hereby revised by the addition of the following at the end
     of the section:

     Any revision to an existing Applicable List Price shall take effect at the
     end of the calendar quarter following the calendar quarter in which Primus
     provides notification to Distributor of such revision. Any Applicable List
     Price added hereunder shall take effect immediately upon notification by
     Primus.

10.  Section 2.2 is hereby revised by the addition of the following new section
     2.2.5.:

     2.2.5. Right To Modify Portions of the Software When Installing and
     Implementing the Software for End User: A non-exclusive, limited,
     non-transferable license to modify that portion of the Software comprising
     ASP Code. "ASP Code" shall mean that code identified in the Documentation
     as "active server pages code" or "ASP code". In addition, Distributor may

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     create enhancements, integrations or new applications utilizing the open
     API's contained within the Software and may permit Sub-Distributors and End
     Users to do the same, provided that in each case such enhancements,
     integrations or new applications may only be distributed and used in
     connection with use of the Software. Distributor may sublicense to
     Sub-Distributors and End Users the right to modify only those portions of
     the Documentation consisting of the training manuals, by modifying Primus'
     generic content standard and process documents as necessary to meet such
     End User's internal training needs. Section 2.3.1. notwithstanding,
     Distributor is not required to obtain Primus' consent to create or to
     permit Sub-Distributors or End Users to create the modifications,
     enhancements, integrations or new applications (collectively, "Distributor
     Modifications") that are expressly permitted in this Section 2.2.5.
     Distributor assumes full responsibility for any Distributor Modifications
     to the Software. Distributor hereby releases Primus from all liability and
     waives all rights, claims and remedies against Primus, for any and all loss
     and damages of any kind or nature, solely to the extent that they arise out
     of any such Distributor Modifications and shall defend Primus against any
     claim by an unaffiliated third party that Distributor has misappropriate a
     third party's trade secret or the Distributor Modifications infringe the
     third party's copyright, patent, trademark or other intellectual property
     right and pay the amount of any final judgment or settlement to which
     Distributor consents with respect to such claim. Primus shall have no
     support and maintenance obligations whatsoever with respect to Distributor
     Modifications.

11.  Section 2.2 is hereby revised by the addition of the following new section
     2.2.6.:

     2.2.6. Distributor's Obligation to Distribute Current Versions: In the
     event that Primus furnishes Distributor a new version of any of the
     Software products for general commercial distribution (as indicated by
     Primus), including all Updates and changes in performance specifications of
     the Software, Distributor must commence distributing the most recent
     version of such Software within 180 days of Distributor's receipt of the
     new version and thereafter shall not distribute any previous versions of
     such Software.

12.  Section 4.3 is hereby replaced in its entirety with the following:

     4.3 Secondline Support. For the lesser of the Term or for so long as Primus
         ------------------
     is generally making support available to its end users of the applicable
     English language version of the Software, Primus shall provide Distributor
     with Secondline Support for such equivalent version existing in the
     Japanese language. Primus will provide Distributor with Secondline Support
     for a minimum of twelve (12) months after the initial release of a new
     version of a Primus Product for the Territory. Primus shall have no
     obligation to directly support End Users or Sub-Distributors. Primus shall
     not be obligated to provide Secondline Support to Distributor in the event
     that Distributor requests such support with respect to any Sub-Distributor
     or End User that has a total of less than ten (10) licenses of the
     Software. In the event that Primus, in its sole discretion, provides
     support to Distributor with respect to any End User or Sub-Distributor who
     has less than ten (10) licenses of the Software, Primus may limit such
     support as Primus, in its sole discretion, deems appropriate.
     Notwithstanding the foregoing limit on Secondline Support with respect to
     any End User that has a total of less than ten (10) licenses of the
     Software, Primus will provide Secondline Support to up to five (5) such
     small end user accounts, provided Distributor identifies each such account
     as strategic in that it has opportunity for significant additional licenses
     of Software (each, a "Strategic Account"). Primus may, in its discretion,
     cease supporting a Strategic Account if such account has not acquired more
     than ten (10) licenses in the 12 months following the initial sale by
     Distributor.

                                       3

<PAGE>

13.  Section 7.1 is hereby replaced in its entirety with the following:

     Distributor shall pay Primus Software license fees and Primus Maintenance
     fees on Software sub-licensed to End Users and End User Maintenance
     purchased by End Users in accordance with the payment terms of Section 7.7.
     Distributor shall pay Primus (i) the Software license fees for such order
     at the Applicable List Price, less Distributor's Discount in accordance
     with Table B, (ii) the Support and Maintenance fees for each such order,
     calculated by the Support and Maintenance fee (percentage) set forth in
     Table B multiplied by the amount of support and maintenance fees actually
     invoiced by Primus KK and (iii) all related shipping charges, taxes and
     duties. License fees payable or owed to Primus by Distributor shall be paid
     in U.S. Dollars ("Dollars"); provided that the parties may mutually agree
     otherwise in writing on a case by case basis. Primus Maintenance fees
     payable or owed to Primus by Distributor shall be paid in Japanese Yen
     ("Yen"); provided that the parties may mutually agree otherwise in writing
     on a case by case basis.

14.  Section 7.7 is hereby replaced in its entirety with the following:

     7.7. Payment Terms. Unless another date is specified in this Agreement, all
     Primus Software license fee and Primus Maintenance fee payments by
     Distributor to Primus shall be due and payable upon the earlier of (a) the
     fifteenth (15/th/) day of the month following the month in which
     Distributor is actually paid and (b) seventy-five (75) days from the date
     of Primus' invoice. Payment for all other amounts due Primus, if any, shall
     be due within thirty (30) days of Primus' invoice date, unless otherwise
     expressly stated herein. Overdue payments shall accrue interest at the
     lesser of U.S. prime rate on the day of the invoice plus five percent (5%)
     per annum, or the maximum rate permitted by applicable law. Additionally,
     with respect to any amounts to be paid to Primus in Yen, if Distributor
     fails to timely pay an invoice hereunder and if the "Noon Buying Rate" (per
     the then-current Yen-Dollar rate, as quoted by the Federal Reserve Bank of
     New York (12 Noon Foreign Exchange Rates) for the Effective Date of the
     relevant License Agreement (if no rate is published for such day, the next
     day on which the rate is published) provides for more Dollars than on the
     date the invoice is actually paid (the "Currency Exchange Shortfall"),
     Licensee shall pay Primus additional Yen on the actual payment date to make
     up the Currency Exchange Shortfall.

15.  Section 8.1 is hereby replaced in its entirety with the following:

     8.1  License To Use Trademarks. Primus hereby grants Distributor a non-
          -------------------------
     exclusive license, with right to sub-license to Sub-Distributors and End
     Users, to use the Trademarks in the Territory during the Term, solely in
     connection with: (i) the promotion, marketing, licensing, distribution and
     use of the Software; and (ii) the provision of End User Maintenance and of
     implementation and training services related to the Software. Primus
     reserves all other rights to the Trademarks. Distributor shall ensure that
     all use of the Trademarks by Sub-Distributors and End Users complies with
     this Section 8.1 and that Sub-Distributors and End Users comply with the
     obligations of Distributor and the requirements set forth in this Section 8
     in general. Distributor shall, on a quarterly basis, provide Primus with a
     list of all Sub-Distributors and End Users actually using the Trademarks.

16.  No Split on Historical Deals With No New Revenue. Notwithstanding Section
     7.3 of the Agreement or any other provision calling for the payment of a
     portion of license or support and maintenance fees to Distributor, if (1)
     Primus provides Primus Products to an End User located within the Exclusive
     Territory that is a subsidiary or branch office of a Parent Company which
     is a licensed End User located outside the Exclusive Territory pursuant to
     a license agreement or arrangement entered into between Primus and such
     Parent Company

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<PAGE>

     before September 30, 2001, including without limitation, Primus'
     arrangements with Compaq, Hewlett Packard and Oracle Corporation (a
     "Subsidiary License Transfer") and (2) there is no new or additional
     license fee paid to Primus at the time of and in connection with such
     Subsidiary License Transfer, then there shall be no obligation for Primus
     to pay any amount to Distributor in connection therewith. If there is any
     new or additional license fee paid to Primus at the time of and in
     connection with such Subsidiary License Transfer, then Primus will make the
     payments required under Section 7.3 applicable to such new or additional
     payments and Primus will provide Distributor with a statement showing the
     calculation of the payment and the basis thereof. Primus will use its
     commercially reasonable efforts to direct the applicable subsidiary or
     division to Distributor to obtain Japanese language support, if requested,
     in connection with a Subsidiary License Transfer.

17.  Under Section 5.4 and Section 10.1 (if Performance Goals are once again to
     be measured as described therein), the Performance Goals referenced therein
     shall be equal to 5% of Primus United States Recognized Revenue for each
     calendar year throughout the Term hereof, even extending beyond the Initial
     Term. Section 1.38, "Primus Recognized Revenue" is hereby replaced in its
     entirety to read:

           1.38 "Primus United States Recognized Revenue" means the actual
           calendar year recognized revenue for Primus derived from Primus
           Product licenses originated in the United States (i.e., credited to a
           U.S. based sales person or a U.S. based distributor/reseller), which
           revenue is accounted for in accordance with United States "Generally
           Accepted Accounting Principles".

18.  Section 10.1 Term and Automatic Renewal is amended and replaced in its
                  --------------------------
     entirety to read:

     10.1  Term. This Agreement and licenses granted hereunder will commence on
     ----  ----
           the Effective Date and continue in full force and effect perpetually
           unless earlier terminated by mutual agreement of the parties or
           pursuant to this Section 10 (the "Term"). Notwithstanding the
           foregoing sentence, if Distributor has not completed the listing of
           its common stock on a recognized public stock exchange by December
           31, 2004, then Section 10.1 as it exists before this amendment shall
           replace the foregoing sentence as Section 10.1, except the initial
           "Term" will expire on March 31, 2006. Primus will provide Seagate
           Crystal software hereunder only for so long as the terms of its
           agreement with Seagate permits the same.

     Section 10.1.2 (iv) is hereby deleted.

19.  The following sentence of Section 3.1.1 Performance Goals is deleted in its
     entirety: "Without limiting Primus' other remedies, if Distributor fails to
     meet any of the Performance Goals, then Primus may, after consultation with
     Distributor, but in Primus' sole and absolute discretion, change any
     exclusive appointment or license grant to a non-exclusive appointment or
     license grant." The foregoing sentence shall, however, become a part of the
     Agreement (and shall apply with respect to all prior years) without further
     action of the parties if Distributor has not completed the listing of its
     common stock on a recognized public stock exchange by December 31, 2004.

20.  Section 2.3.4 is hereby amended by adding the following new sentence
     thereto: Distributor will not enter into any Sub-Distributor arrangement
     with a term of greater than two (2) years without Primus' prior written
     approval.

21.  Paragraphs 18 and 19 of this Amendment shall not be effective unless
     Distributor pays all currently outstanding Primus invoices, whether or not
     currently due by their terms

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     (including invoice # INV004458 in the amount of $69,496.59) on or before
     November 20, 2001.

22.  The following new Section 5.5 shall be added to the Agreement:

     "5.5 Source Code Escrow and Release. In order to ensure that Distributor
     remains able to enjoy its license rights, and to meet its maintenance
     obligations, as stated under this Agreement, Primus shall maintain the
     source code for the Primus Products in escrow. Licensee shall be named as a
     FlexSAFE beneficiary in accordance with Article 2 of the FLEX-SAFE Escrow
     Agreement that Primus has entered into with Data Securities International,
     a copy of which is attached hereto as Schedule 1 (the "Escrow Agreement").
                                           ----------
     Primus shall enroll Licensee as a FlexSAFE beneficiary within thirty (30)
     business days of the Effective Date. Primus shall deposit all source code
     for the Primus Products into the escrow account, as called for in the
     Escrow Agreement. Licensee shall reimburse Primus for fees paid by Primus
     with respect to Licensee's subscription to the escrow account. Primus will
     deposit with the escrow agent a full copy of the computer source code for
     all Primus Products then licensed to Distributor. Such deposit shall be
     updated by Primus within a reasonable time of each commercially released
     Update. If any of the following conditions exists uncorrected for more than
     thirty (30) days: (a) entry of an order for relief against Primus under
     Title 11 of the United States Code; (b) Primus' making a general assignment
     for its creditors; or (c) the appointment of a general receiver or trustee
     in bankruptcy of Primus' business or property; then Primus shall grant
     Licensee a limited, non-exclusive, non-transferable license to copy and use
     the source code for the versions of the Primus Products for which it was
     receiving support immediately prior to such cessation, solely for the
     purpose of distributing, supporting and maintaining the Primus Products
     under the terms, conditions and restrictions of this Agreement, including
     without limitation the payment obligations to Primus hereunder. Licensee
     shall treat the source code with the same degree of care and security as it
     treats its own commercially valuable source code, and at least a reasonable
     standard of care. Any license granted pursuant to this subsection shall
     terminate and Licensee shall return the source code and all copies thereof
     to Primus in the event that Primus or another entity resumes the technical
     support services to which Licensee would have been entitled under this
     Agreement with respect to the Primus Products. THE SOURCE CODE WILL BE
     PROVIDED TO DISTRIBUTOR ON AN AS IS BASIS, AND PRIMUS EXPRESSLY DISCLAIMS
     ALL AND ANY EXPRESS OR IMPLIED WARRANTIES RELATING TO THE SOURCE CODE. If
     Primus becomes unable or unwilling to perform any of its material
     obligations to Distributor under this Agreement after the expiration of any
     applicable cure period, Primus will provide to Distributor the computer
     source code for all Primus Products then licensed to Distributor under the
     above stated license and use terms and the terms and conditions of this
     Agreement (as such breach by Primus will not be a release condition under
     the above described escrow agreement).

Except as expressly stated above, this letter addendum provides no other
consent, express or implied, to materially modify the License Agreement.

                                       6

<PAGE>

Please indicate your agreement to this letter by executing the enclosed
duplicate in the space provided below. This Addendum One shall be effective as
of August 1, 2001 (the "Effective Date").

Sincerely,                                       Agreed and Accepted:

Primus Knowledge Solutions, Inc.                 Primus Knowledge Solutions, KK

/s/ Michael A. Brochu

                                                 By: /s/ Masahiro Sasaki

Michael A. Brochu                                Name:   Masahiro Sasaki

President and Chief Executive Officer            Its:    CEO and President

                                                 Date:   November 7, 2001

                                       7

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