The present disclosure provides a method and system for performing unification of data of one or more users across a plurality of communication devices in a plurality of shards. A user unification system receives a first set of data. In addition, the user unification system maps the first set of data to a first natural number. Further, the user unification system assigns a first shard index to the first set of data. Furthermore, the user unification system obtains a second set of data. Moreover, the user unification system maps the second set of data to a second natural number. Also, the user unification system unifies the first natural number and the second natural number. Also, the user unification system assigns the first shard index to the second set of data associated with a first user of the one or more users.