Great Support Bot

Great Support Bot follows the same forward-and-reply pattern as most feedback bots, adding a few conveniences: a customisable welcome message with buttons, an optional group with topic mode so several admins can each own their own conversation thread, broadcasts back to everyone who wrote in, and UTM tags to trace which channel post or link brought a message.

It advertises itself simply as free and built on the JustBot.me platform. There is no public monthly-user figure to gauge how widely it is used, so weigh it as a lightweight, no-frills alternative to Livegram or SUCH rather than a proven high-scale option.