Channel Corp.

If you thought there’s only so much you could do to engage in online customer’s journey, think again. 
Designed to capture potential customers before they leave your site and increase conversions, the web-based SaaS lets you see who’s on your site, what they’re looking at, how long/frequent they’re visiting and finally, drop in and give a little “hello” to online customers in real time. Actively engage in customer journey through conversations, and manage those conversations and customers by segmenting them into groups of your choice.

Channel.io

Channel is a conversational CRM solution that helps online businesses to capture potential customers before they leave the websites.

Facebook

Communicate with customers on your website with Messenger-powered chat. Chat Plugin is a chat widget maintained by the Meta Business that enables live chat on your website.
Whether they’re on their computer or their phone, website visitors will be able to message you anytime by clicking on a small Messenger chat bubble in the lower right corner of your site.
Key features:
<ul>
<li>Website visitors can message you while browsing your site.</li>
<li>Set up auto-replies and answers to common questions to serve customers when you’re not available.</li>
<li>Continue the conversation with customers on Messenger even after they leave your website.</li>
<li>Visitors without a Facebook Messenger account can ask you questions anonymously in Guest mode.</li>
<li><a href="https://www.facebook.com/business/messenger/get-started" rel="nofollow ugc">Messenger</a>’s familiar interface builds trust.</li>
<li>No need to switch between apps to answer questions you get on the website.</li>
</ul>

Facebook Chat Plugin – Live Chat Plugin for WordPress

The Facebook Chat Plugin makes it easy for your website visitors to chat with you and ask you questions, even if they don't have Messenger.

Channel.io vs Facebook Chat Plugin – Live Chat Plugin for WordPress