NIHON ARIBA K.K.

                            STOCK PURCHASE AGREEMENT

                          DATED AS OF OCTOBER 19, 2000

* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  


<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                             Page
                                                                             ----
<S>                                                                          <C>
1    Issuance and Sale of Common Stock.........................................1
     1.1      Closing..........................................................1

2    Representations and Warranties of the Company.............................1
     2.1      Organization.....................................................1
     2.2      Corporate Power..................................................2
     2.3      Capitalization...................................................2
     2.4      Authorization; Enforceability; Shares............................2
     2.5      Consents.........................................................2
     2.6      No Conflicts.....................................................3
     2.7      Contracts........................................................3
     2.8      Financial Statements.............................................3
     2.9      Liabilities......................................................3
     2.10     Litigation.......................................................3
     2.11     Commercial Registration..........................................4
     2.12     Compliance with Laws.............................................4
     2.13     Brokers or Finders...............................................4
     2.14     Affiliate Relationships..........................................4

3    Representations and Warranties of the Investors...........................4
     3.1      Organization.....................................................4
     3.2      Corporate Power..................................................4
     3.3      Authorization....................................................4
     3.4      Governmental Consents............................................4
     3.5      No Conflicts.....................................................4
     3.6      Litigation.......................................................5
     3.7      Investment Intent................................................5
     3.8      No Public Market.................................................5
     3.9      Brokers or Finders...............................................5
     3.10     Tax Advisors.....................................................5
     3.11     Access to Management.............................................5

4    Covenants Prior to the Closing Date.......................................5
     4.1      Commercially Reasonable Efforts..................................5
     4.2      Indemnification of Officers and Directors........................6

5    Conditions of the Investors' Obligations at Closing.......................6
     5.1      Representations and Warranties...................................6
     5.2      Covenants........................................................6
     5.3      Certificate......................................................6
     5.4      Securities Laws..................................................6
     5.5      Proceedings and Documents........................................6
     5.6      Authorizations...................................................6
</TABLE>

* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  



                                       i
<PAGE>

<TABLE>
<S>                                                                          <C>
     5.7      Board of Directors...............................................6
     5.8      Transaction Agreements...........................................6
     5.9      Opinion of Counsel...............................................6
     5.10     No Injunctions or Regulatory Restraints..........................7

6    Conditions of the Company's Obligations at Closing........................7
     6.1      Representations and Warranties...................................7
     6.2      Covenants........................................................7
     6.3      Certificate......................................................7
     6.4      Permits..........................................................7
     6.5      Proceedings and Documents........................................7
     6.6      Payment of Purchase Price........................................7
     6.7      Transaction Agreements...........................................7
     6.8      No Injunctions or Regulatory Restraints..........................7
     6.8      Board of Directors...............................................7

7    Covenants of the Parties..................................................8
     7.1      Revenue Commitment...............................................8
     7.2      License of Software Products....................................11
     7.3      Confidentiality.................................................12
     7.4      Governmental Filings............................................13

8    Term and Termination.....................................................13
     8.1      Term............................................................13
     8.2      Termination.....................................................13

9    Miscellaneous............................................................14
     9.1      Governing Law; Dispute Resolution...............................14
     9.2      Notices and Other Communications................................14
     9.3      Language........................................................16
     9.4      Severability....................................................16
     9.5      References; Subject Headings....................................16
     9.6      Further Assurances..............................................16
     9.7      Expenses........................................................16
     9.8      No Waiver.......................................................16
     9.9      Entire Agreement; Amendments....................................16
     9.10     Assignment......................................................17
     9.11     No Agency.......................................................17
     9.12     No Beneficiaries................................................17
     9.13     Counterparts....................................................17
</TABLE>

* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  


                                       ii
<PAGE>

                          LIST OF EXHIBITS AND SCHEDULE

EXHIBITS

EXHIBIT 2.1     Articles of Incorporation
EXHIBIT 2.11    Commercial Register
EXHIBIT 5.8(a)  Shareholders Agreement
EXHIBIT 5.9     Opinion of Counsel for the Company

SCHEDULE OF EXCEPTIONS

* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  


                                       iii
<PAGE>


                                NIHON ARIBA K.K.
                            STOCK PURCHASE AGREEMENT


         THIS STOCK PURCHASE AGREEMENT (this "AGREEMENT") is made as of the 
19th day of October, 2000 (the "EFFECTIVE DATE"), by and among Nihon Ariba 
K.K., a Japanese corporation (the "COMPANY"), SOFTBANK Corp., a Japanese 
corporation ("SOFTBANK PARENT") and SOFTBANK E-Commerce Corp., a Japanese 
corporation and direct wholly owned subsidiary of SOFTBANK Parent ("SOFTBANK" 
and together with SOFTBANK Parent, the "INVESTORS").

         THE PARTIES HEREBY AGREE AS FOLLOWS

         1.       ISSUANCE AND SALE OF COMMON STOCK. Subject to the terms and 
conditions hereof, the Company will issue and sell to each of the Investors 
and each of the Investors will buy from the Company 1,900 shares of the 
Company's common stock (the "SHARES"), for an aggregate of 3,800 Shares.

                  1.1      CLOSING. The closing of the purchase and sale of 
the Shares hereunder (the "CLOSING") shall be held at the offices of Morrison 
& Foerster LLP, 1-1-3 Marunouchi, Chiyoda-ku, Tokyo 100-0005, Japan no later 
than December 31, 2000 or at such earlier time and place as shall be mutually 
agreed upon by the Company and the Investors (the date and time of the 
Closing is hereinafter referred to as the "CLOSING DATE"). At the Closing, 
the Investors shall purchase the Shares at US$10,526.31 per Share, for an 
aggregate purchase price of US$40,000,000, and the Company shall register the 
Investors as the owners of the Shares on the Company's shareholder register.

         2.       REPRESENTATIONS AND WARRANTIES OF THE COMPANY.

         The Company hereby represents and warrants to the Investors that, 
except as set forth on a schedule of exceptions (the "SCHEDULE OF 
EXCEPTIONS") furnished to the Investors concurrently herewith:

                  2.1      ORGANIZATION. The Company was incorporated on 
December 28, 1999 as a Kabushiki Kaisha (a joint-stock company). The 
registered office of the Company is at Shinjuku Park Tower 7-1, 
Nishi-Shinjuku 3-chome, Shinjuku-ku, Tokyo. The Company has been duly 
incorporated and is a validly existing corporation under the laws of Japan 
and has full power and authority to carry on its business as contemplated in 
this Agreement, that certain License Agreement by and between the Company and 
Ariba, Inc. ("ARIBA") (the "LICENSE AGREEMENT") and that certain Shareholders 
Agreement by and among the Investors, Ariba and the Company (the 
"SHAREHOLDERS AGREEMENT" together with this Agreement, the License Agreement 
and any other agreement entered into which specifically states that it shall 
be treated as a Transaction Agreement, "TRANSACTION AGREEMENTS"). A true and 
correct copy of the Articles of Incorporation of the Company (the "ARTICLES") 
is attached hereto as EXHIBIT 2.1. In the event of any discrepancy between 
the provisions of this Agreement and the provisions of the Articles, the 
provisions of this Agreement shall prevail.

* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  



<PAGE>

                  2.2      CORPORATE POWER. The Company has all requisite 
legal and corporate power and authority (a) to execute and deliver each 
Transaction Agreement to which the Company is a party, (b) to sell and issue 
the Shares hereunder, and (c) to carry out and perform its obligations under 
the terms of each Transaction Agreement to which it is a party.

                  2.3      CAPITALIZATION.

                           (a)      As of the Closing, the Company's 
authorized capital stock will consist of 20,900 shares of Common Stock, no 
par value, of which 5,225 shares will be issued and outstanding. Ariba 
currently owns and will own, immediately prior to the Closing, all of the 
Company's issued and outstanding capital stock.

                           (b)      The Company plans to adopt a stock plan, 
under which [*] shares of Common Stock will be reserved for the grant of 
options and/or stock purchase rights of employees, officers, directors and 
consultants of the Company. No options, warrants, stock purchase rights, 
shares or other securities have been issued under such plan.

                           (c)      Except as contemplated by the Transaction 
Agreements, there are no options, warrants or commitments of any kind 
relating to the capital stock of the Company, including any preemptive or 
other rights to purchase its capital stock.

                  2.4      AUTHORIZATION; ENFORCEABILITY; SHARES. All 
corporate  action on the part of the Company, its directors and shareholders 
that is necessary for the authorization, execution, delivery and performance 
of the Transaction Agreements by the Company, the authorization, sale, 
issuance and delivery of the Shares and the performance of the Company's 
obligations under each Transaction Agreement to which it is a party has been 
duly and validly taken or will be duly and validly taken prior to the 
Closing. This Agreement, when executed and delivered by the Investors, and 
each other Transaction Agreement to which the Company is a party, when 
executed and delivered at the Closing, shall constitute the legal and binding 
obligation of the Company, enforceable in accordance with its terms, subject 
to laws of general application relating to bankruptcy, insolvency and the 
relief of debtors and other laws of general application affecting enforcement 
of creditors' rights generally, rules of law governing specific performance, 
injunctive relief or other equitable remedies and limitations of public 
policy. The Shares, when issued in compliance with the provisions of this 
Agreement, will be validly issued, fully paid and nonassessable; will have 
the voting powers, preferences, rights, qualifications, limitations and 
restrictions described in the Articles; and will be free of any liens, 
encumbrances, restrictions, claims or charges of any kind or nature; 
PROVIDED, HOWEVER, that the Shares may be subject to restrictions on transfer 
under applicable securities laws and pursuant to the Transaction Agreements.

                  2.5      GOVERNMENTAL CONSENT, ETC. No consent, approval or 
authorization of or designation, declaration or filing with any governmental 
authority on the part of the Company is required in connection with the valid 
execution and delivery of the Transaction Agreements, or the offer, sale or 
issuance of the Shares, or the consummation of any other transaction 
contemplated by the Transaction Agreements, except the qualification (or 
taking of such action as may be necessary to secure an exemption from 
qualification, if available) of the offer and sale 



* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  

                                       2
<PAGE>

of the Shares under applicable securities laws, which filings and 
qualifications, if required, will be accomplished in a timely manner within 
the applicable periods therefore.

                  2.6      NO CONFLICTS. The Company's execution, delivery 
and performance of the Transaction Agreements will not (i) violate the 
Articles or any provision of applicable law, (ii) violate any applicable 
rule, regulation, judgment, order, writ, injunction or decree of any 
governmental body or court, (iii) have any effect on the compliance of the 
Company with any applicable licenses, permits or authorizations which would 
materially and adversely affect the Company, (iv) result in the breach of, 
give rise to a right of termination, cancellation or acceleration of any 
obligation with respect to (presently or with the passage of time), or 
otherwise be in conflict with any term of, or affect the validity or 
enforceability of, any contract, agreement or other commitment to which the 
Company is a party and which would materially and adversely effect the 
Company, or (v) result in the creation of any lien upon any assets of the 
Company; provided, however, that regulatory approval may be required in 
connection with conducting the Company's business and the Company makes no 
representation with respect to any such approvals.

                  2.7      CONTRACTS. The Company has not entered into any 
contracts except for contracts entered into in the ordinary course of the 
Company's business and that are not material to the Company, individually or 
in the aggregate. Each of the Company's material contracts is valid and in 
full force and effect. The Company has duly performed its obligations under 
each of its contracts. No breach of or default under any contract by the 
Company has occurred, and no event has occurred which would (with the passage 
of time, the giving of notice or both) cause or give rise to such a breach or 
default by the Company. To the Company's knowledge, no breach of or default 
under any of the Company's contracts by any Person other than the Company has 
occurred, and no event which would (with the passage of time, the giving of 
notice or both) cause or give rise to such a breach or default by any such 
Person has occurred.

                  2.8      FINANCIAL STATEMENTS. The Company has delivered to 
the Investors its financial statements (balance sheet and income statement), 
for the fiscal period ending September 30, 2000 (the "FINANCIAL STATEMENTS"). 
The Financial Statements have been prepared in accordance with U.S. GAAP 
applied on a consistent basis throughout the periods indicated, except that 
the Financial Statements may not contain all footnotes required by U.S. GAAP. 
The Financial Statements fairly present the financial condition, operating 
results and cash flows of the Company as of the dates and for the periods 
indicated therein, subject to normal year-end audit adjustments.

                  2.9      LIABILITIES. Except as set forth in the Financial 
Statements, the Company has no material liabilities, contingent or otherwise, 
other than (i) liabilities incurred in the ordinary course of business 
subsequent to September 30, 2000 and (ii) obligations under contracts and 
commitments incurred in the ordinary course of business and not required 
under U.S. GAAP to be reflected in the Financial Statements, which, in both 
cases, individually or in the aggregate, are not material to the financial 
condition or operating results of the Company.

                  2.10     LITIGATION. There are no actions, proceedings or 
investigations before any court or governmental agency pending or, to the 
Company's knowledge, threatened in writing against the Company or its 
properties.

* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  



                                       3
<PAGE>

                  2.11     COMMERCIAL REGISTRATION. A certified copy of the 
commercial register of the Company (and a true and complete English 
translation thereof) is attached to this Agreement as EXHIBIT 2.11, and all 
information contained therein is current, complete and accurate.

                  2.12     COMPLIANCE WITH LAWS. The Company has complied 
with, is not in violation of, and has not received any notices of violation 
with respect to, any applicable law with respect to the conduct of its 
business, except where such violation or lack of compliance would not have a 
material effect on the Company.

                  2.13     BROKERS OR FINDERS. The Investors have not and 
will  not incur, directly or indirectly, as a result of any action taken by 
the Company, Ariba or their respective Affiliates, any liability for 
brokerage or finders' fees or agents' commissions or any similar charges in 
connection with this Agreement or the transactions contemplated hereby.

                  2.14     AFFILIATE RELATIONSHIPS. Except as expressly 
contemplated by the Transaction Agreements, SECTION 2.14 of the Schedule of 
Exceptions identifies all contracts between the Company, on the one hand, and 
Ariba, its Affiliates or any of their respective officers or directors, on 
the other hand.

         3.       REPRESENTATIONS AND WARRANTIES OF THE INVESTORS.

         Each of the Investors hereby represents and warrants jointly and 
severally that:

                  3.1      ORGANIZATION. The Investor has been duly 
incorporated, and is a validly existing corporation under the laws of Japan 
and has full power and authority to enter into and perform each Transaction 
Agreement to which it is a party.

                  3.2      CORPORATE POWER. The Investor has all requisite 
legal and corporate power (a) to execute and deliver each Transaction 
Agreement to which it is a party and (b) to carry out and perform its 
obligations under the terms of each such agreement.

                  3.3      AUTHORIZATION. The Investor has the full power and 
authority to execute, deliver and perform each Transaction Agreement to which 
it is a party and purchase and pay for the Shares. This Agreement, when 
executed and delivered by the Company, and each other Transaction Agreement 
to which the Investor is a party, when executed and delivered on or before 
the Closing, shall constitute the legal and binding obligation of the 
Investor, enforceable in accordance with its terms, subject to laws of 
general application relating to bankruptcy, insolvency and the relief of 
debtors and other laws of general application affecting enforcement of 
creditors' rights generally, rules of law governing specific performance, 
injunctive relief and other equitable remedies and limitations of public 
policy.

                  3.4      GOVERNMENTAL CONSENT, ETC. No consent, approval or 
authorization of or designation, declaration or filing with any governmental 
authority on the part of the Investor is required in connection with the 
valid execution and delivery of the Transaction Agreements or the 
consummation of any other transaction contemplated by the Transaction 
Agreements.

                  3.5      NO CONFLICTS. The Investor's execution, delivery 
and performance of this Agreement will not (i) violate the Articles of 
Incorporation of the Investor or any provision of 

* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  


                                       4
<PAGE>

applicable law, (ii) violate any applicable rule, regulation, judgment, 
order, writ, injunction or decree of any governmental body or court, (iii) 
have any effect on the compliance of the Investor with any applicable 
licenses, permits or authorizations which would materially and adversely 
affect the Investor, (iv) result in the breach of, give rise to a right of 
termination, cancellation or acceleration of any obligation with respect to 
(presently or with the passage of time), or otherwise be in conflict with any 
term of, or affect the validity or enforceability of, any contract, agreement 
or other commitment to which the Investor is a party and which would 
materially and adversely effect the Investor, or (v) result in the creation 
of any lien upon any assets of the Investor.

                  3.6      LITIGATION. There are no actions, proceedings or 
investigations pending or, to the Investor's knowledge, threatened in writing 
against the Investor or its properties before any court or governmental 
agency.

                  3.7      INVESTMENT INTENT. The Investor is acquiring the 
Shares for investment for its own account, not as a nominee or agent, and not 
with a view to, or for resale in connection with, any distribution thereof.

                  3.8      NO PUBLIC MARKET. The Investor understands that no 
public market now exists for any of the securities issued by the Company and 
that the Company has made no assurances that a public market will ever exist 
for the Company's securities.

                  3.9      BROKERS OR FINDERS. The Company and Ariba have not 
and will not incur, directly or indirectly, as a result of any action taken 
by the Investor, any liability for brokerage or finders' fees or agents' 
commissions or any similar charges in connection with this Agreement or the 
transactions contemplated hereby.

                  3.10     TAX ADVISORS. The Investor has reviewed with its 
own tax advisors the tax consequences of the transactions contemplated by 
this Agreement. It relies solely on such advisors and not on any statements 
or representations of the Company or any of the Company's agents with respect 
to such tax consequences. It understands that it, and not the Company, shall 
be responsible for its own tax liability that may arise as a result of the 
transactions contemplated by this Agreement.

                  3.11     ACCESS TO MANAGEMENT. The Investor has had an 
opportunity to discuss the Company's business, management and financial 
affairs with the Company's management and has had access to all other 
information about the Company it deemed necessary in connection with the 
purchase of the Shares. The Investor has also had the opportunity to ask 
questions of officers of the Company and understands that such discussions, 
as well as any written information issued by the Company, were intended to 
describe certain aspects of the Company's business and prospects but were not 
a thorough or exhaustive description.

         4.       COVENANTS PRIOR TO THE CLOSING DATE.

                  4.1      COMMERCIALLY REASONABLE EFFORTS. The Company, 
Ariba and the Investors will use commercially reasonable efforts to effect 
the Closing as soon as possible but in no event later than December 31, 2000.

* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  


                                       5
<PAGE>

                  4.2      INDEMNIFICATION OF OFFICERS AND DIRECTORS. The 
Company has established or shall establish policies providing customary 
indemnification protection for its directors and officers and shall provide 
the Investors with a reasonable opportunity to review and comment on such 
policies.

         5.       CONDITIONS OF THE INVESTORS' OBLIGATIONS AT CLOSING.

         The Investors' obligation to effect the Closing is, unless waived by 
each of the Investors in writing, subject to the fulfillment of the following 
conditions:

                  5.1      REPRESENTATIONS AND WARRANTIES. The 
representations and warranties made by the Company in SECTION 2 shall be true 
and correct in all material respects as of the date hereof and as of Closing 
Date.

                  5.2      COVENANTS. All covenants, agreements and 
conditions contained in this Agreement to be performed or complied with by 
the Company on or prior to the Closing Date shall have been performed or 
complied with in all material respects.

                  5.3      CERTIFICATE. The Company shall have delivered to 
the Investors a certificate in form and substance satisfactory to the 
Investors, dated as of the Closing Date and signed by an executive officer of 
the Company, to the effect that the conditions set forth in SECTIONS 5.1 and 
5.2 have been satisfied.

                  5.4      SECURITIES LAWS. The Company shall have filed a 
Securities Notice (YUKASHOKEN TSUCHISHO) with the Kanto Finance Bureau as 
required by the Securities and Exchange Law of Japan for the offer and sale 
of the Shares.

                  5.5      PROCEEDINGS AND DOCUMENTS. All corporate and other 
proceedings of the Company in connection with the transactions contemplated 
hereby and all documents and instruments incidental to such transactions 
shall be reasonably satisfactory in substance and form to the Investors.

                  5.6      AUTHORIZATIONS. All authorizations, approvals or 
permits, if any, of any governmental authority or regulatory body that are 
required in connection with the lawful issuance and sale of the Shares 
pursuant to this Agreement shall have been duly obtained and shall be 
effective on and as of the Closing.

                  5.7      BOARD OF DIRECTORS. [*] shall have been elected to 
the Board of Directors.

                  5.8      TRANSACTION AGREEMENTS. The Shareholders Agreement 
in the form attached hereto as EXHIBIT 5.8(a), and each other Transaction 
Agreement shall have been executed and delivered by each party thereto other 
than the Investors.

                  5.9      OPINION OF COUNSEL. The Investors shall have 
received from Asahi Law Offices, counsel for the Company, an opinion, dated 
as of the Closing, in substantially the form attached hereto as EXHIBIT 5.9.


* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  


                                       6
<PAGE>

                  5.10     NO INJUNCTIONS OR REGULATORY RESTRAINTS. No 
temporary restraining order, preliminary or permanent injunction or other 
order issued by any court of competent jurisdiction or governmental or 
regulatory authority or other legal or regulatory restraint or prohibition 
preventing the consummation of the Closing shall be in effect.

         6.       CONDITIONS OF THE COMPANY'S OBLIGATIONS AT CLOSING.

         The Company's obligation to effect the Closing is, unless waived in 
writing by the Company, subject to the fulfillment of the following 
conditions:

                  6.1      REPRESENTATIONS AND WARRANTIES. The 
representations made in SECTION 3 by each of the Investors shall be true and 
correct in all material respects as of the date hereof and as of the Closing 
Date.

                  6.2      COVENANTS. All covenants, agreements, and 
conditions contained in this Agreement to be performed or complied with by 
the Investor on or prior to the Closing Date shall have been performed or 
complied with in all material respects.

                  6.3      CERTIFICATE. Each of the Investors shall have 
delivered to the Company a certificate in form and substance satisfactory to 
the Company, dated as of the Closing Date and signed by an executive officer 
of each of the Investors, to the effect that the conditions set forth in 
SECTIONS 6.1 and 6.2 have been satisfied.

                  6.4      PERMITS. All permits, authorizations, consents, 
licenses or approvals of all relevant governmental or regulatory authorities 
required for the execution and consummation by the Investors of the 
transactions contemplated by the Transaction Agreements shall have been duly 
obtained.

                  6.5      PROCEEDINGS AND DOCUMENTS. All corporate and other 
proceedings of each Investor in connection with the transactions contemplated 
hereby and all documents and instruments incidental to such transactions 
shall be reasonably satisfactory in substance and form to the Company.

                  6.6      PAYMENT OF PURCHASE PRICE. The Investors shall 
have delivered to the Company the purchase price for the Shares.

                  6.7      TRANSACTION AGREEMENTS. Each Transaction Agreement 
shall have been executed and delivered by each party thereto other than the 
Company and Ariba.

                  6.8      NO INJUNCTIONS OR REGULATORY RESTRAINTS. No 
temporary restraining order, preliminary or permanent injunction or other 
order issued by any court of competent jurisdiction or governmental or 
regulatory authority or other legal or regulatory restraint or prohibition 
preventing the consummation of the Closing shall be in effect.

                  6.9      BOARD OF DIRECTORS. [*] and [*] shall be available 
to serve on the Board of Directors if nominated by the Company.



* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  


                                       7
<PAGE>

         7.       COVENANTS OF THE PARTIES.

                  7.1      REVENUE COMMITMENT.

                           (a)      REVENUE TARGETS. The Revenue Targets for
each Revenue Period are as follows:

<TABLE>
<CAPTION>
         Revenue Period           Revenue Target                Revenue Date
         --------------           --------------                ------------
<S>                               <C>                        <C>
               1                       [*]                           [*]
               2                       [*]                           [*]
               3                       [*]                           [*]
               4                       [*]                           [*]
               5                       [*]                           [*]
               6                       [*]                           [*]
               7                       [*]                           [*]
               8                       [*]                           [*]
</TABLE>

[*]

[*]



* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  

                                       8
<PAGE>

<TABLE>
<CAPTION>
    Revenue Period           Reduced Revenue Target       Shifted Amount       Revised Total
    --------------           ----------------------       --------------       -------------
<S>                          <C>                          <C>                  <C>
           1                          [*]                       [*]                 [*]
           2                          [*]                       [*]                 [*]
           3                          [*]                       [*]                 [*]
           4                          [*]                       [*]                 [*]
           5                          [*]                       [*]                 [*]
           6                          [*]                       [*]                 [*]
           7                          [*]                       [*]                 [*]
           8                          [*]                       [*]                 [*]
           9                          [*]                       [*]                 [*]
          10                          [*]                       [*]                 [*]
</TABLE>

                           (b)      NOTICE OF REVENUE. Within ten (10) days 
after the end of each Revenue Period, the Company will provide each Investor 
with a report, prepared in accordance with the Company's records, summarizing 
in reasonable detail the Qualifying Revenues earned by the Company for such 
Revenue Period, with appropriate documentation reasonably requested by the 
Investors to verify the calculation of such Qualifying Revenues set out in 
the report (the "QUALIFYING REVENUE REPORT").

                           (c)      If a [*] exists for a Revenue Period, 
then within ten (10) days after receiving the Qualifying Revenue Report, 
SOFTBANK shall cause the Company to receive an amount of [*] equal to the [*] 
(including such [*] as may be purchased by SOFTBANK or its Affiliate (as 
defined in the Shareholders Agreement) as well as by any [*]) to the extent 
permitted in the following sentence. [*]



* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  

                                       9
<PAGE>

                           (d)      NOTICE OF OBJECTION. After any payment or 
purchase has been made in compliance with SECTION 7.1(c) for any Revenue 
Period and within sixty (60) days from the Revenue Date for such period (the 
"OBJECTION NOTICE PERIOD"), either Investor may give the Company written 
notice that such Investor or both Investors object to the calculation of 
Qualifying Revenues set forth in such Qualifying Revenue Report (the 
"OBJECTION NOTICE"). Upon receipt of any Objection Notice, the parties will 
use reasonable efforts to resolve any objections. If the parties are unable 
to resolve the dispute within twenty (20) days from the date of the Objection 
Notice, the parties will jointly select an accounting firm of international 
standing to resolve the dispute. If the parties are unable to agree on the 
choice of such an accounting firm, they will select an accounting firm of 
international standing by lot (other than any accounting firms for any of the 
parties) (the "ACCOUNTANT") which shall determine the Qualifying Revenue for 
the applicable Revenue Period. The Accountant shall deliver to each of the 
parties its determination within twenty (20) days after being selected, and 
the determination of the Accountant shall be binding upon the parties. The 
expenses of the Accountant shall be borne equally by the parties, provided 
that if the Investors' objection is resolved in the Investors' favor, the 
Company shall reimburse the Investor to the extent required so that the 
amount paid by the Investor pursuant to Section 7.1 less the amount of such 
reimbursement is in accordance with the resolution of the dispute.

                           (e)      The Company shall maintain complete and 
accurate accounting records in accordance with sound accounting principles 
and will preserve such records for a period of at least two (2) years. The 
Investors may semi-annually, or at such additional time at the Investors' 
request, audit, or hire an independent auditor to audit, the operations, 
books and records of the Company required to be maintained pursuant to this 
Section.

                           (f)      As used herein, unless otherwise defined, 
the following capitalized terms have the following respective meanings:

                                    (i)      [*]  Potential customers of the 
Company (A) listed on a schedule approved by the Company and the Investors on 
or before the execution of this Agreement or (B) mutually agreed upon by the 
Company and the Investors as follows:

Prior to commencing substantial sales efforts with respect to any potential 
[*] (a "Target"), SOFTBANK shall notify the Company in writing identifying 
such Target, and provide Company with any such documentation relating to such 
Target as may be reasonably requested by Company. [*]

* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  

                                       10
<PAGE>

                                    (ii)     [*] A localized [*] 
language version of Ariba Marketplace.

                                    (iii)    [*] The aggregate Revenue 
received from and only from each [*] (A) for support for the first year for 
which support is rendered to such [*] (but no subsequent years) and (B) for 
product licensing (but not any revenue or other credit from consulting, 
maintenance, training, education or other professional services).

                                    (iv)     REVENUE: Revenue shall mean (i) 
revenue that is recognized in accordance with Ariba's revenue recognition 
policies as then in effect, and (ii) cash payments received by the Company 
which are recognizable in accordance with U.S. GAAP and are not subject to 
any contingencies. For purposes of clause (ii) above, such payments shall be 
considered "Revenue" regardless of whether the Company actually recognizes 
such payments as revenue so long as the payments are recognizable as defined 
in clause (ii) above. Any amounts credited as "Revenue" pursuant to clause 
(i) above for which cash is not collected ("Uncollectible Amount") by the end 
of the quarter immediately following the Revenue Period in which such 
"Revenue" is recognized (the "Next Revenue Period"), shall result in an 
increase in the Revenue Target (on a dollar for dollar basis) for the Revenue 
Period immediately following the Next Revenue Period equal to the 
Uncollectible Amount.

                                    (v)      REVENUE DATE: The last day of 
each respective Revenue Period as set forth in SECTION 7.1(a).

                                    (vi)     REVENUE PERIOD: The three month 
periods set forth in SECTION 7.1(a), to which the Revenue Target apply and 
any subsequent three month periods as necessary for any Shifted Amount.

                                    (vii)    REVENUE TARGET: The targeted 
level of Qualifying Revenue for each Revenue Period as set forth in SECTION 
7.1(a), as adjusted pursuant to SECTION 7.1(a).

                                    (viii)   [*] shall mean, for any Revenue 
Period, the amount, if any, by which the Qualifying Revenue is [*] than the 
Revenue Target, provided that such [*] shall be [*] on a dollar-for-dollar 
basis by an amount equal to the amount, if any, by which the aggregate amount 
of Qualifying Revenue for all prior Revenue Periods, including the aggregate 
amount of Qualifying Revenues that the Company receives for prior Revenue 
Periods pursuant to Section 7.1(c), exceeds the sum of the Revenue Targets 
for all prior Revenue Periods.

                                    (ix)     U.S. GAAP: Generally accepted 
accounting principles of the United States of America.

                  7.2      LICENSE OF SOFTWARE PRODUCTS. The Company and [*] 
shall negotiate in good faith toward [*] license of Software Products (as 
defined in the License Agreement) on terms and conditions acceptable to the 
parties, resulting in Qualifying Revenues no less than [*]. The terms of the 
license shall require payment in full by [*], with the specific payment 
schedule to be set forth in the agreement. 

* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  

                                       11
<PAGE>

The parties shall use all diligent efforts to execute and deliver an 
agreement by [*].

                  7.3      CONFIDENTIALITY.

                           (a)      The Investors recognize that, in 
connection with the performance of this Agreement, the Company may disclose 
Confidential Information (as defined below) to the Investors. For purposes of 
this Agreement, "CONFIDENTIAL INFORMATION" means (i) proprietary information 
(whether owned by the Company or a third party to whom the Company owes a 
non-disclosure obligation) regarding the Company's business or (ii) 
information which is marked as confidential at the time of disclosure to the 
Investors, or if in oral form, is identified as confidential at the time of 
oral disclosure. Confidential Information shall not include information 
which: (A) was known to the Investors at the time of the disclosure by the 
Company; (B) has become publicly known through no wrongful act of the 
Investors; (C) has rightfully been received by the Investors from a third 
party without an obligation of confidentiality; or (D) has been independently 
developed by the Investors. Each of the Investors agrees (x) not to use any 
such Confidential Information for any purpose other than in the performance 
of its obligations under this Agreement and (y) not to disclose any such 
Confidential Information, except (1) to its employees who are reasonably 
required to have the Confidential Information in connection herewith or with 
any of the other Transaction Agreements, (2) to its agents, representatives, 
lawyers and other advisers that have a need to know such Confidential 
Information or (3) pursuant to, and to the extent of, a request or order by a 
court or other governmental authority; PROVIDED that such parties undertake 
in writing (or are otherwise bound by rules of professional conduct) to keep 
such information strictly confidential. Each of the Investors agrees to take 
all reasonable measures to protect the secrecy and confidentiality of, and 
avoid disclosure or unauthorized use of, the Company's Confidential 
Information.

                           (b)      Each of the Investors acknowledges and 
agrees that (i) its obligations under this SECTION 7.3 are necessary and 
reasonable to protect the Company and its business, (ii) any violation of 
these provisions could cause irreparable injury to the Company for which 
money damages would be inadequate, and (iii) as a result, the Company shall 
be entitled to obtain injunctive relief against the threatened breach of the 
provisions of this SECTION 7.3 without the necessity of proving actual 
damages. Each of the Investors agrees that the remedies set forth in this 
SECTION 7.3 are in addition to and in no way preclude any other remedies or 
actions that may be available to the Company at law or under this Agreement.

                           (c)      Each of the Investors agrees that the 
terms and conditions of this Agreement and the Transaction Agreements shall 
be treated as Confidential Information and that no reference thereto shall be 
made without the prior written consent of the Company (which consent shall 
not be unreasonably withheld) except (a) as required by applicable law 
including, without limitation, by the U.S. Securities and Exchange Commission 
and Japanese governmental authorities and relevant stock exchanges or 
markets, (b) to its accountants, banks, financing sources, lawyers and other 
professional advisors, PROVIDED that such parties undertake in writing (or 
are otherwise bound by rules of professional conduct) to keep such 
information strictly confidential, (c) in connection with the enforcement of 
this Agreement, (d) in connection with a merger, acquisition or similar 
transaction or (e) pursuant to joint press releases mutually agreed to by the 
parties to be prepared in good faith.



* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  

                                       12
<PAGE>

                  7.4      GOVERNMENTAL FILINGS.

                  If any Japanese withholding taxes are imposed on dividends 
payable to the Investors by the Company, the Company shall withhold such 
amounts, pay the same to the Japanese tax authority, and promptly furnish the 
Investors with appropriate documentation of the amounts so withheld as soon 
as practicable. The Company shall cooperate with the Investors to make and 
necessary filings to utilize the lowest withholding rate available under any 
treaty between Japan and the United States.

         8.       TERM AND TERMINATION.

                  8.1      TERM. This Agreement shall be effective as of the 
Effective Date and shall continue in effect until and unless terminated 
pursuant to SECTION 8.2.

                  8.2      TERMINATION. This Agreement may be terminated as 
follows:

                           (a)      Upon the parties' mutual written 
agreement.

                           (b)      If any of the Company, Ariba or either 
Investor fails to perform, in any material respect, any of its material 
obligations hereunder or under any of the other Transaction Agreements, and 
if such default continues for a period of thirty (30) days after the date the 
defaulting party first receives written notice of such default from either 
Investor (if Ariba or the Company is the defaulting party) or Ariba or the 
Company (if either of the Investors is the defaulting party), then either 
Investor (if Ariba or the Company is the defaulting party) or the Company (if 
either of the Investors is the defaulting party) shall have the right to 
terminate this Agreement effective immediately upon written notice to the 
defaulting party at any time after such thirty (30)-day period.

                           (c)      The Investors shall have the right to 
terminate this Agreement, effective immediately upon written notice to Ariba 
and the Company, in the event that either Ariba or the Company has elected to 
terminate [*] in accordance with its terms.

                           (d)      Notwithstanding the foregoing, the right 
of the Investors to terminate this Agreement pursuant to Section 8.2(b), as a 
result of a default of the Company, or pursuant to Section 8.2(c), as a 
result of a termination of [*] by the Company, shall exist only if [*] and 
only if no [*] (as defined in the Shareholders Agreement) is in effect.

                           (e)      Any of the Company, SOFTBANK or SOFTBANK 
Parent shall have the right to terminate this Agreement, effective 
immediately upon written notice to the other party, if the Closing has not 
occurred on or before December 31, 2000.

                           (f)      Any of the Company or the Investors shall 
have the right to terminate this Agreement, effective immediately upon 
written notice to the other party, in the event that the Company (where an 
Investor is the party giving notice) or an Investor (where the Company is the 
party giving notice) is dissolved, liquidated or declared bankrupt or a 
filing for 



* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  

                                       13
<PAGE>

voluntary or involuntary bankruptcy, civil rehabilitation or for the 
application of other similar insolvency or rehabilitation procedures is made 
by such party.

                           (g)      Notwithstanding the foregoing, SECTION 
7.3 and ARTICLE 9 (except for SECTION 9.6, which shall not survive 
termination) shall survive a termination of the Agreement. Termination of 
this Agreement for any reason shall not release any party from any liability 
or obligation which has already accrued as of the effective date of such 
termination, and shall not constitute a waiver or release of, or otherwise be 
deemed to prejudice or adversely affect, any rights, remedies or claims, 
whether for damages or otherwise, which a party may have hereunder, at law, 
equity or otherwise or which may arise out of or in connection with such 
termination.

         9.       MISCELLAect the 
validity or enforceability of any agreement or other commitment to which 
Ariba is a party and which would materially and adversely affect Ariba, or 
(v) result in the creation of any lien, pledge, mortgage, claim, charge or 
encumbrance upon any assets of Ariba.

* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  



                                       17
<PAGE>

                           (f)      LITIGATION. There are no actions, suits 
or proceedings pending or, to Ariba's knowledge, threatened, against Ariba 
before any court or governmental agency which question Ariba's right to enter 
into or perform this Agreement or other Transaction Agreements to which it is 
a party, or which question the validity of this Agreement or any of the other 
Transaction Agreements.

                           (g)      DISCLOSURE. No representation or warranty 
by Ariba contained in this Agreement or any other Transaction Agreement to 
which it is a party, and no exhibit, writing or other instrument required to 
be furnished pursuant hereto contains any untrue statement of a material fact 
or omits any material fact necessary in order to make the statements and 
information contained herein or therein not misleading.

         24.      EFFECTIVENESS, TERM AND TERMINATION.

                  24.1     TERM. This Agreement shall be effective as of the 
Effective Date and shall continue in effect until and unless terminated 
pursuant to Section 24.2.

                  24.2     TERMINATION. This Agreement may be terminated as 
follows:

                           (a)      Upon the Parties' mutual written agreement.

                           (b)      By either Ariba or the Company, effective 
immediately upon written notice to the other Parties, if either SOFTBANK 
Parent or SOFTBANK breaches any material provision of this Agreement or of 
any of the other Transaction Agreements in any material respect and such 
breach continues for a period of thirty (30) days after the delivery of 
written notice of the default, describing the default in reasonable detail.

                           (c)      By either SOFTBANK Parent or SOFTBANK, 
effective immediately upon written notice to the other Parties, if Ariba or 
the Company breaches any material provision of this Agreement or of any of 
the other Transaction Agreements in any material respect and such breach 
continues for a period of thirty (30) days after the delivery of written 
notice of the default, describing the default in reasonable detail.

                           (d)      By either SOFTBANK Parent or SOFTBANK, 
effective immediately upon written notice to Ariba and the Company, in the 
event that either Ariba or the Company terminates or elects to terminates [*] 
in accordance with its terms.

                           (e)      Ariba, effective immediately upon written 
notice to the other Parties in the event that either Ariba or the Company has 
elected to terminate [*] in accordance with its terms.

                           (f)      By either SOFTBANK Parent, SOFTBANK, 
Ariba or the Company, effective immediately upon written notice to the other 
Parties, in the event that any other Party is dissolved, liquidated or 
declared bankrupt or a filing for voluntary or involuntary.

                           (g)      Notwithstanding the foregoing, the right 
of SOFTBANK and SOFTBANK Parent to terminate this Agreement pursuant to 
Section 24.2(c), as a result of a breach by the Company, or pursuant to 
Section 24.2(d), as a result of a termination of [*],


* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.

                                       18
<PAGE>

shall exist only if [*] and only if no [*] is in effect.

                  24.3     CONTINUING LIABILITY. Notwithstanding the 
foregoing, Article 25 and Article 26 (except for Section 26.6, which shall 
not survive termination) shall surviverovision shall be construed, to the extent 
feasible, so as to render the provision enforceable, and if no feasible 
interpretation would save such provision, it shall be severed from the 
remainder of this Agreement which shall remain in full force and effect 
unless the severed provision is essential and material to the rights or 
benefits received by any party. In such event, the parties shall use best 
efforts to negotiate, in good faith, a substitute, valid and enforceable 
provision or agreement which most nearly affects the parties' intent in 
entering into this Agreement.

                  9.5      REFERENCES; SUBJECT HEADINGS. Unless otherwise 
indicated, references to Sections and Exhibits herein are to Sections of and 
Exhibits to, this Agreement. The subject headings of the Sections of this 
Agreement are included for the purpose of convenience of reference only, and 
shall not affect the construction or interpretation of any of its provisions.

                  9.6      FURTHER ASSURANCES. The parties shall each perform 
such acts, execute and deliver such instruments and documents, and do all 
such other things as may be reasonably necessary to accomplish the 
transactions contemplated in this Agreement.

                  9.7      EXPENSES. Each of the parties will bear its own 
costs and expenses, including, without limitation, fees and expenses of legal 
counsel, accountants, brokers, consultants and other representatives used or 
hired in connection with the negotiation and preparation of this Agreement 
and consummation of the transactions contemplated hereby. All such expenses 
incurred by the Company shall be borne by the Company to the maximum extent 
permitted by applicable law including, without limitation, expenses relating 
to the formation of the Company, any transfer taxes for transfer of the 
Company stock to the parties, registration charges, taxes, fees and expenses 
relating to required governmental or regulatory approvals, notary fees and 
legal fees and expenses.

                  9.8      NO WAIVER. No waiver of any term or condition of 
this Agreement shall be valid or binding on a party unless the same shall 
have been set forth in a written document, specifically referring to this 
Agreement and duly signed by the waiving party. The failure of a party to 
enforce at any time any of the provisions of this Agreement, or the failure 
to require at any time performance by one or both of the other parties of any 
of the provisions of this Agreement, shall in no way be construed to be a 
present or future waiver of such provisions, nor in any way affect the 
ability of a party to enforce each and every such provision thereafter.

                  9.9      ENTIRE AGREEMENT; AMENDMENTS. The terms and 
conditions contained in this Agreement (including the Schedules and Exhibits 
hereto), the other Transaction Agreements and the Ariba Non-Disclosure 
Agreement dated October 19, 2000 by and between Ariba and the 



* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  

                                       16
<PAGE>

Investors constitute the entire agreement between the parties and supersede 
all previous agreements and understandings, whether oral or written, between 
the parties with respect to the subject matter hereof. No agreement or 
understanding amending this Agreement shall be binding upon any party unless 
set forth in a written document which expressly refers to this Agreement and 
which is signed and delivered by duly authorized representatives of each 
party.

                  9.10     ASSIGNMENT. No party shall assign this Agreement 
or any rights or obligations hereunder without the other parties' prior 
written consent, except that (i) the Company may assign this Agreement to a 
Person into which it has merged or which has otherwise succeeded to all or 
substantially all of the Company's business or assets and (ii) the Investors 
may assign this Agreement to a Person that is a wholly owned subsidiary of 
SOFTBANK Parent or a Person who has succeeded to all or substantially all of 
SOFTBANK Parent's business or assets. All assignees under this SECTION 9.10 
must assume in writing or by operation of law, the assigning party's 
obligations under this Agreement, PROVIDED, HOWEVER, that the assigning party 
shall remain liable for the assignee's performance of its obligations 
hereunder. This Agreement shall inure to the benefit of, and shall be binding 
upon, the parties and their respective permitted successors and assigns.

                  9.11     NO AGENCY. The parties are independent 
contractors. Nothing contained herein or done in pursuance of this Agreement 
shall constitute any party the agent of any other party for any purpose or in 
any sense whatsoever.

                  9.12     NO BENEFICIARIES. Nothing herein express or 
implied, is intended to or shall be construed to confer upon or give to any 
person, firm, corporation or legal entity, other than the parties and their 
affiliates who hold securities (and, in the case of the Investors, any 
affiliates of SOFTBANK Parent), any interests, rights, remedies or other 
benefits with respect to or in connection with any agreement or provision 
contained herein or contemplated hereby.

                  9.13     COUNTERPARTS. This Agreement may be executed in 
any number of counterparts, and each counterpart shall constitute an original 
instrument, but all such separate counterparts shall constitute only one and 
the same instrument.

* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  



                                       17
<PAGE>


         IN WITNESS WHEREOF, the parties have executed this Agreement as of 
the date first above written.

                                  COMPANY:

                                  NIHON ARIBA K.K.



                                  By:   /s/ KEITH J. KRACH
                                      ------------------------------------------
                                  Title:   Chairman & CEO
                                         ---------------------------------------



                                  INVESTORS:

                                  SOFTBANK E-COMMERCE CORP.



                                  By:   /s/ KEN MIYAUCHI
                                      ------------------------------------------
                                  Title:
                                         ---------------------------------------



                                  SOFTBANK CORP.



                                  By:   /s/ MASAYOSHI SON
                                      ------------------------------------------
                                  Title:
                                         ---------------------------------------

* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  



<PAGE>

                                   EXHIBIT 2.1

                            Articles of Incorporation


* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  



<PAGE>




                                  EXHIBIT 2.11

                               Commercial Register

* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  


<PAGE>




                                 EXHIBIT 5.8(a)

                             Shareholders Agreement


* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.  


<PAGE>




                                   EXHIBIT 5.9

                       Opinion of Counsel for the Company



* Represents confidential information for which Ariba, Inc. is seeking 
  confidential treatment with the Securities and Exchange Commission.