Whatsapp I am using since 2011 from that time the service of whatsapp is really good. Whatsapp is the app which keep me in touch with my friends and relatives all the time cuz its a cost free and ad free application. On whatsapp I can make a good clearity of voice calls and same for video calls. Most good thing of whatsapp I like is they continiously make good changes in their app which is so useful in now a days.