Do only Shiites call Ali ibn Abi Talib "Imam"?

My question is whether calling Ali "Imam Ali" is a shibboleth that reveals that someone is a Shiite or not. I know the basic historical-political and doctrinal differences, including the imamate and the Shia belief that Ali was to be the temporal and spiritual leader of the Islamic community after the death of Muhammad. I assumed, then, that only Shiites would refer to him as "Imam Ali" and that Sunnis would just call him "Ali" or maybe "Caliph Ali." However, today I heard a non-Shiite scholar referring to him as Imam Ali, hence my question. Do non-Shia call him Imam Ali, too? When I search for "Imam Ali" online it seems that all the results are from Shia sources. Thank you in advance.