EXHIBIT 5.1

                     [MORRISON & FOERSTER LLP LETTERHEAD]

                               January 27, 2000

EarthWeb Inc.
3 Park Avenue
New York, New York  10016

Gentlemen:

     At your request, we have examined the Registration Statement on Form S-8
executed by you on January 27, 2000, and to be filed with the Securities and
Exchange Commission in connection with the registration under the Securities Act
of 1933, as amended, of an aggregate of 392,708 shares of your common stock,
$.01 par value (the "Common Stock") which will be issuable under the 1998 Stock
Incentive Plan, as amended, and the 1998 Employee Stock Purchase Plan, as
amended (the "Plans").

     As your counsel in connection with the Registration Statement, we have
examined the proceedings taken by you in connection with the adoption of the
Plans and the authorization of the issuance of the shares of Common Stock under
the Plans (the "Plan Shares") and such documents as we have deemed necessary to
render this opinion.

     Based upon the foregoing, it is our opinion that the Plan Shares, when
issued and outstanding pursuant to the terms of the Plans, will be validly
issued, fully paid and non-assessable shares of Common Stock.

     We consent to the use of this opinion as an exhibit to the Registration
Statement.

                              Very truly yours,

                              /s/MORRISON & FOERSTER LLP
                              __________________________
                              MORRISON & FOERSTER LLP