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
Usabilla Visual Survey - Gather feedback at any stage of the design process.
Doorbell.io - Collect in-app user feedback. Available on websites, iOS, and Android.
1Flow - The leading in-app survey platform for mobile apps and websites to collect in-the-moment user feedback. Measure NPS, CSAT, CES, and PMF scores and gather feature-specific user feedback to improve your product.
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.