Various methods and systems for facilitating network traffic monitoring in association with an application running on a client device are provided. In this regard, aspects of the invention facilitate monitoring network traffic being transmitted to and/or from a client device, such as a mobile device, so that network performance can be analyzed. In various implementations, one or more default classes associated with an application on a device are replaced with one or more custom monitoring classes designed to facilitate monitoring data packets being communicated to or from the application. The custom monitoring classes can then be utilized to facilitate monitoring a plurality of data packets communicated to or from the application.