GPT-3 AI is an open-source natural language processing (NLP) model developed by OpenAI. It is not technically free, as there are fees associated with using the model. However, OpenAI has made the GPT-3 AI model available to developers and researchers for free through its API Service, which allows developers and researchers to access the model without having to purchase a license or pay a subscription fee. This makes GPT-3 AI much more accessible to a wider range of developers and researchers than many other AI models.