When it comes to agreeing with someone, there are many ways to express it beyond the common phrase "saw eye to eye". Other synonyms include "concur", "be in harmony", "see things the same way", "be on the same page", "share the same opinion", "have a mutual understanding", "reach a consensus", "be of like mind", "think alike", "be on board", and "be in accord". These phrases can be used in both informal and formal situations, depending on the context. Regardless of which term is used, the important thing is to communicate that two or more people are in agreement on a certain topic or matter.