For the word-processing phenomenon, see Cupertino effect. Cupertino (/ˌkuːpərˈtiːnoʊ/ KOOP-er-TEEN-oh) is a U.S. city in Santa Clara County, California, directly west of San Jose on the western edge of the Santa Clara Valley with portions extending into the foothills of the Santa Cruz Mountains. The population was 58,302 as of the 2010 census.