CiNii (/ˈsaɪniː/)[1] is a bibliographic database service for material in Japanese academic libraries, especially focusing on Japanese works and English works published in Japan.

An early trial version of the database was a component of its predecessor called GeNii, [2] available online at least since June 2002.

[4] The service searches from within the databases maintained by the NII itself (Citation Database for Japanese Publications, CJP), as well as the databases provided by the Japan Science and Technology Agency (J-STAGE), the National Diet Library of Japan, institutional repositories, and other organizations.

[5] As of March 2020, the database contains more than 22 million articles from more than 3,600 publications.

Although the database is multidisciplinary, the largest portion of the queries it receives is in the humanities and social sciences field, perhaps because CiNii is the only database that covers Japanese scholarly works in this field (as opposed to the natural, formal, and medical sciences which benefit from other databases).