Quacquarelli Symonds (QS): data is from Scopus and surveys
THE World University Rankings: by Times Higher Education Supplement (THES), uses Web of Science and survey data.
Academic Ranking of World Universities (ARWU): by Shanghai Jiao Tong University. Uses data from Web of Science data including winners of Nobel Prize and Fields Medal
Leiden Ranking/ Leiden University, data is from Web of Science.
SCImago Institutions Rankings: by SCImago Lab, uses data from Scopus.
Webometrics Ranking of World Universities: By the Cybermetrics Lab of the Spanish National Research Council (CSIC). Covers 20,000 universities.