Since the release of GPT-2, OpenAI has steadily shifted toward a more closed and proprietary approach to its LLM development — until now. The recent release of open-weight models marks a notable change in direction, and it’s not happening in a vacuum.

Despite the company's name, OpenAI hasn't dropped an open version of its AI models since GPT-2 in 2019. That changed on Tuesday, as CEO Sam Altman shared two new open-weights, reasoning AI models, named gpt-oss-120b (120 billion parameters) and gpt-oss-20b (20 billion parameters).

OpenAI announced a new free and open GPT model that Microsoft has made available for Windows. The model is a gpt-oss-20b, available on AI Foundry, and is planned to come soon to the macOS. It's built for code execution and tool use,