How can I add a chat app to my front store?

ExpandCart has the most powerful chat application at front online stores its Zendesk 

This application provides your customers with chat support directly from the storefront.
You can create an account via the following link

https://www.zopim.com/?aref=ODk1OTI:1UT7sD:US9DSGS4icuUZ3v95uJwVNYJL5M

After you active the account you can add your data inside the application setting at your store, by going from store Control Panel to apps and services and then Entering Zendesk Live Chat application

You can enable and disable this app for specifc pages or for all pages. And you can display it on the right or left sides.

 This application is free on all plans 

On the next link you can learn more about the prices of plans with the applications attached with each one

https://www.expandcart.com/en/online-stores-pricing