GPT-trainer

This one is really solid and massive. I agree with other reviewers that this one deserves much more attention compared to other AI chatbots. We tried a handful of such tools before and usually refunded since essential features were often hastily implemented. This one has a mature API and "has been around" for a while.
So far we are very pleased with responsiveness of the tool and will stack up not to miss out on this before thorough testing.