Exhibit 5.1


               [LETTERHEAD OF WILSON SONSINI GOODRICH & ROSATI]

                               October 12, 2000

InfoSpace, Inc.
601 108/th/ Ave N.E
Suite 1200
Bellevue, Washington  98004

     RE: REGISTRATION STATEMENT ON FORM S-8

Ladies and Gentlemen:

     We have examined the Registration Statement on Form S-8 to be filed by
InfoSpace, Inc. (the "Company") with the Securities and Exchange Commission on
or about October 12, 2000 (the "Registration Statement") in connection with the
registration under the Securities Act of 1933, as amended, of 30,965,291 shares
of the Company's common stock (the "Shares") to be issued upon exercise of stock
options granted pursuant to the Go2Net, Inc. 2000 Stock Option Plan, the Go2Net,
Inc. 1996 Stock Option Plan, the Silicon Investor, Inc. 1996 Stock Plan, the
Web21 Stock Option Plan, the Authorize.Net Corporation 1999 Stock Incentive
Plan, and the IQC Corporation Option to Purchase Common Stock (collectively, the
"Plans"). As legal counsel for the Company, we have examined the proceedings
proposed to be taken in connection with the issuance and sale of the Shares to
be issued under the Plans.

     In arriving at the opinion expressed below, we have examined and relied on
the following documents:

          1.   The Restated Certificate of Incorporation and the Restated Bylaws
               of the Company;

          2.   The records of meetings and written consents of the Board of
               Directors and stockholders of the Company and Go2Net, Inc.
               provided to us by the Company;

          3.   The Plans; and

          4.   The Agreement and Plan of Reorganization dated July 26, 2000, by
               and between the Company, Giants Acquisition Corp., and Go2Net,
               Inc.

     In addition, we have examined and relied upon the originals or copies,
certified or otherwise identified to our satisfaction, of all such corporate
records of the Company and such other instruments and other certificates of
public officials, officers and representatives of the Company and such other
persons, and we have made such investigations of law, as we have deemed
appropriate as a basis for the opinions expressed below.


     Based upon the foregoing, it is our opinion that:

          1.   The Company has corporate power adequate for the issuance of the
               Shares in accordance with the S-8 Registration Statement.

          2.   The Company has taken all necessary corporate action required to
               authorize the issuance and sale of the Shares.

          3.   When certificates for the Shares have been duly executed and
               countersigned, and delivered against due receipt of the exercise
               price for the Shares as described in the options relating thereto
               and the Plans, the Shares will be legally and validly issued,
               fully paid and nonassessable.

     We consent to the use of this opinion as an exhibit to the Registration
Statement and further consent to the use of our name wherever appearing in the
Registration Statement, including any Prospectus constituting a part thereof,
and any amendments thereto.

                                     Very truly yours,

                                     WILSON SONSINI GOODRICH & ROSATI
                                     Professional Corporation

                                     /s/ Wilson Sonsini Goodrich & Rosati P.C.