Want to integrate some chat application in my website

Want to integrate some chat application in my website

 

Dear Members,
I am looking for a free chat application to my business website. I have seen many websites, as soon as we open webpage, the chat window also opens, asking for help.

One important question - Integrating such applications are good? Or should I continue with skype? but you know skype is not a pure such application.

Will be there any affect of ranking of my website?