Platforma - Wireframe library of layouts and UI elements
SendBird - SendBird is messaging-as-a-service.
Contra Wireframe Kit - Open source wireframe kit for design and prototyping 🚀
Chat by Stream - Build and ship in app messaging in a few hours
Source Wireframe Kit - Library of 537 blocks for desktop and mobile prototyping
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.