1. WhatsApp Messenger

whatsapp.com
Play Store: WhatsApp Messenger (Price: Free)

2. Messenger

messenger.com
Play Store: Messenger (Price: Free)

3. WeChat

wechat.com
Play Store: WeChat (Price: Free)

4. Line

line.me
Play Store: LINE: Free Calls & Messages (Price: Free)

5. Viber

viber.com
Play Store: Viber (Price: Free)

6. Google Allo

allo.google.com
Play Store: Google Allo

7. Lite Messenger for Facebook (Android, iOS) (Free)

Play Store: Lite Messenger for Facebook

8. Telegram (Android, iOS) (Free)

telegram.org
Play Store: Telegram

9. Signal (Android, iOS) (Free)

Play Store: Signal Private Messenger

10. Tango (Free)

wtango.me
Play Store: Free Video Calls & Text