The phrase "in existence" can be replaced with a variety of synonyms, depending on the context of the sentence. Some options include "existing," "present," "current," "operative," "running," "extant," "alive," "ongoing," "in operation," and "functional." Each of these alternatives can convey a slightly different meaning or nuance to the reader or listener. For example, "current" might suggest that something is happening right now, while "extant" implies a historical or archaeological meaning. Choosing the most appropriate synonym for "in existence" is crucial for conveying the intended message effectively, so it's always important to consider the context and connotations of each option.