The race to enlist the world’s universities in the movement for free online education accelerated Tuesday as the Web site edX announced that it has added 15 new schools, more than doubling the size of the venture, with new partners from Asia, Europe and Australia.

EdX, a nonprofit organization in Cambridge, Mass., founded by the Massachusetts Institute of Technology and Harvard University, competes with for-profit Coursera and other providers of massive open online courses, or MOOCs.

Until Tuesday, edX counted 12 institutions in its partnership, including Georgetown University. Now it has 27.

Coursera, based in Mountain View, Calif., has 70 institutions.

Both sites launched last year.

The schools joining edX include several from Asia: Tsinghua and Peking universities in mainland China; the University of Hong Kong; Hong Kong University of Science and Technology; Kyoto University in Japan; and Seoul National University in South Korea.

Among the others were Cornell University, of New York, Boston University and Davidson College, of North Carolina, as well as the University of Queensland in Australia and three schools from Europe.

Coursera recently announced that Yale University, of Connecticut, had joined its efforts. Now the only Ivy League school unaffiliated with either major MOOC site is Dartmouth College.