Crisp is all in one customer messaging platform. It gives you features like realtime chats (textual and video), emails, chatbots and knowledge base pages. The biggest competitor to Crisp is Intercom which gives similar features and is currently have a bigger market size as opposed to other chat tools.
Crisp has a foreever free but limited plan which gives you 2 seats and is pretty good for starting businesses however they do not include integrations or knowledge base in this plan. The next plan starts from $25 which gives you 4 seats however they do not offer any knowledge base and many integrations even in this plan. Then there is a $95 plan which includes all of this and allows no-branding as well.
Yes, Crisp has mobile apps for Android as well as for iOS platforms. It even has desktop apps for Mac and Windows.
Intercom is more widely used in comparison to Crisp. However, Intercom is costly as oppose to Crisp. There are a few things that Crisp does not offer like rich user profiles, live customer data or realtime customer segments.