Whats up stranger is a free Android app developed by App Qi. This app falls under the Social & Communication category. The app's main feature is that it allows you to send WhatsApp messages to people without first adding them to your contact list. This can be useful when you want to send a quick message to someone who is not on your contact list.

The app's interface is straightforward and easy to use. You simply need to enter the phone number of the person you want to message, and then the app will open the WhatsApp chat window for that number. You can then type your message and hit send. The app also allows you to send media files like photos, videos, and documents.

Overall, Whats up stranger is a useful app for those who frequently send messages to people who are not on their contact list. The app is easy to use and does not require any complicated setup. However, it is important to note that this app only works with WhatsApp and does not support other messaging platforms.