Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
UseResponse - Open-source, self-hosted customer feedback software, live chat and helpdesk system that you can install on your server. Organize documentation using knowledge base and get feedback from social networks with centralized system
WATI - No-code chatbot builder for WhatsApp Business
UserVoice - UserVoice integrates easy-to-use feedback, helpdesk, and knowledge base management tools in one platform that empowers users to speak and companies to understand.
SleekFlow.io - Sell, convert & support better on chat
Front - multi-channel inbox service for collaborative teams