Thank you for adding a correction. I shouldn’t have been so flippant: OpenAI did not invent transformers, GPT-3 is an iteration of the BERT architecture, which is an encoder, whereas GPT is a decoder model.

Regardless, a GPT model is not a proprietary technology you must get from OpenAI. You’re right that this tool uses OpenAI’s API, but this isn’t necessarily implied by the use of GPT.