The API allows you to fine-tune existing models on your own dataset [1]
[1] Cf second paragraph of https://openai.com/blog/openai-api/
Re:OpenAI API
by YeGoblynQueenne on Friday June 12, 2020 @02:48PM
(#23502377)
"fine tuning", i.e. transfer learning is still limited by the training of the original model.
For instance, if the original model is trained on English text exclusively and you want to fine-tune it on Greek text you are S.O.L.
To clarify: MS windows is closed source, but you can't very well train a large GPT model unless you're someone with the resources of OpenAI. So you're stuck with whatever they choose to train and make available to you.