MopEye is a very useful app that measures mobile apps' network performance and enables you to compare different apps' performance. By using this app, you are contributing the performance data to our study. We will in turn give you more knowledge about the performance of applications installed on your phone. We intend to make this a long-term study. As a participant, you will obtain: (1) the raw and statistical data on different apps' network performance; (2) the list-view comparison of network performance. It is worth noting that our study will not cause any foreseeable risks or discomforts to the subjects. To guarantee your confidentiality and privacy, (1) we will *not* use a remote VPN server to forward your traffic (all forwarding is done inside phone). (2) we will only collect the non-person-identifiable information including per-app performance data (those you see on MopEye's UI), device hardware information (no IMEI, and ANDROID_ID is hashed with salt), signal strength, and coarse-grained location data. (3) we will transmit the collected information to server using the standard encryption method via HTTPS. (4) we will *not* record your mobile browsers' traffic for better privacy. More information is available in the app-side term-of-use dialog.