OpenAI released a new free and open GPT model yesterday that can run on a PC, and now Microsoft is making that easy to do for Windows users. The lightweight gpt-oss-20b model is now available on Windows AI Foundry, and will be coming soon to macOS, too.

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).

We all know AI relies on open-source software, but most of the big AI companies avoid opening their code or their large language model (LLM) weights. Today, things have changed. OpenAI, the artificial intelligence titan behind ChatGPT,