You can track 2 numbers and compare the simultaneous in and outs.
You can track any person you want with OnLog and you get an instant notice when the person you track is online in WhatsApp.
Further you can even see him/her even if the other party blocks you.
You can track him/her even if his/her last seen is closed and you can get his/her in and outs as instant notice.
You can learn how many minutes s/he stays online during the day in total moreover you can track how long s/he stays online weekly and monthly with detailed reports.
The best WhattsApp tracking application working with 100% finding rate.

Waiver: This application doesn’t belong to Whatsapp.