Ask HN: Website live chat- worth it, and who to use? 14 years ago
I don't have any numbers regarding conversions but based on a lot of the providers I've seen, SnapEngage seems like one of the easiest to implement and operate (and is priced pretty reasonably depending on your needs). They do have a free plan, but it's kind of 'hidden' on the pricing page. Www.SnapEngage.com.