I tried a few but was not satisfied with current options until I built my own solution with @LearndCX (twitter username). You should also check out @HelpkitHQ o

I tried a few but was not satisfied with current options until I built my own solution with @LearndCX (twitter username). You should also check out @HelpkitHQ on Twitter, they're doing a great job in my opinion especially with a dev doc.