What are the support chats?

Question

PHP

Good day to all.
Can you please tell me some kind of chat (to embed it on your site) for the support service, which works in this way -
1) the client enters the client part of the site (using the "Support Service" button) where the form for entering a question to the service will be located support
2) the client enters his question, presses send and the letter with the question goes to the e-mail of the support service
3) the support service, having received the letter, clicks in this letter on a special link that opens in the admin browser. part of the site with a response form for the client, having answered the question, this answer appears in the client part, on the same page as the form for sending the question (just below).
Plus, a user notification should appear, for example, an e-mail, a pop-up window with a notification that he was answered (when entering the client part), or just a number on the "Support Service" button in the style of missed SMS or calls .
Perhaps something close, but which requires a "file".

Answer 1

I use "SiteHeart" on some sites...

Answer 2

I saw on one site they used chatzilla with plugins for this.

Answer 3

without file - kayako

Answer 4

zopim, olark and many many many