VK is a social network for Russian-speaking people. It is the most popular social network in Russia.

VKontakte application is a tool that allows you to receive instant notifications when one of your friends, acquaintances, or your significant other, logs in to VKontakte.

To receive such notifications, you need to have the application "VK Online" installed on your device.

This tool allows you to add friends by name, city, and even by ID. 

You can also add people to the list if you want to receive a notification every time they go online. They won't know if you added them.

Furthermore, this app saves the online statuses of all the friends you add and enables you to view their browsing history.