What are some alternatives?
When comparing Bizpopuli and Doorbell.io, you can also consider the following products
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.
UserSnap - Usersnap Track is your central place to organize user feedback and collect bug reports. One screenshot is all it takes. Get rid of endless email exchanges and coffee-stained sticky notes. Your new life is awaiting you!
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
UserEcho - Online customer support solution - Feedback Forum, Helpdesk (ticketing service), Knowledge Base and Live Chat by UserEcho
UserReport - Free online usability surveys with demographic information. Detailed click tracking for websites and feedback button for online user forum. Easy signup.
Invision - Prototyping and collaboration for design teams