If so, did you find that they helped conversions at all? I see these types of things popping up on more and more sites now.
I know @Alex_Scovell did some A/B testing around a similar tool just not sure if it was one of these two.
You can ping him on Slack for more details.
Based on my experience, it really comes down to the nature of the offer. It works well sometimes for eCommerce but not so much for lead generation.