Instant messenger, often shortened to IM is one type of communication service that allows person to have a conversation (chat) privately with others via the internet. Within the calls & messaging on Android and iOS operating systems, they both have an equal value in the terms of innovation and performance. In this work, we focus on evaluate the performance of the IM application on Android and iOS operating systems used several criteria; delay, packet size, and throughput. We use two methods of data collection; primary and secondary data, and compare the IM application using simulation methods. Input parameters for this simulation is in the stanza form of a text message, and the output consists of delay, packet size, and throughput. The results of this work indicate that the IM on iOS operating system with criteria of delay, packet size and throughput can send and receive messages faster than IM on android operating system.