WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
GBWhatsapp - GBWhatsApp is a similar version for WhatsApp Plus have many new features
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Last seen tracker for WhatsApp - Last seen tracker for WhatsApp app helps you save all your WhatsApp data on the internal storage to view all your recent conversations at a glance.
Zulip - Chat for distributed teams. Zulip combines the immediacy of real-time chat with an email threading model. With Zulip, you can catch up on important conversations while ignoring irrelevant ones.
WaStat – WhatsApp tracker - WaStat – WhatsApp tracker app shows the last online time of a phone number at a glance, so you can contact them whenever they get online to share something important to them.