Facebook WhatsApp is a FREE messaging and video calling app. It is used by over 2 billion people in more than 180 countries. It's simple, reliable, and private, so you can easily keep in touch with your friends and family. WhatsApp works on mobile and desktop devices even with slow connections, without subscription costs. All you need is your phone number, no username or login. You can quickly view your contacts who are on WhatsApp and start sending messages.
Supported Android Devices : [4.1–4.3.1] Jelly Bean - [4.4–4.4.4] KitKat - [5.0–5.0.2] Lollipop - [6.0 - 6.0.1] Marshmallow - [7.0 – 7.1.1] Nougat - [8.0-8.1] Oreo -  Pie