SendBird

Sendbird is used as a messaging and Chat API for Mobile Apps and Websites. It offers scalability for a massive audience. It also prevents spam flooding of chat rooms.

Features:
1. Read and track the status of the messages sent to users
2. Integrate bots to assist with customer support and product recommendations
3. Offers Push Notifications & Callbacks
4. Read Receipt & Delivery Status
5. Automatically split or merge chat rooms on the audience volume to offer continues engagement

More Information and Official Website:
Download : https://sendbird.com/