The gotcha for this is that you have to actually use the resources on your free instance or they will reclaim it. I use my instance as a Minecraft server so it utilizes about half of the 24GB RAM you get. For a very light compute task like a chat bot, it might be difficult to keep the instance from being reclaimed.
From this page:
Idle Always Free compute instances may be reclaimed by Oracle. Oracle will deem virtual machine and bare metal compute instances as idle if, during a 7-day period, the following are true:
CPU utilization for the 95th percentile is less than 15% Network utilization is less than 15% Memory utilization is less than 15% (applies to A1 shapes only)
That is a lot of wood