What are the chats for the site (not wordpress) with history?

Question

HTML

Gentlemen, I need to be able to place a chat on the site, in which the history of the client and the operator was saved. It is necessary that the client comes for example in a week and all messages remain (including messages of the operator). That is, as in VK. And so does the operator. It is not necessary that the chat be placed on all pages, it can be a separate one.

Answer 1

My answer is chatra.io

Answer 2

www.siteheart.com - very handy creature