Welcome to AI Decoded, Fast Company’s weekly newsletter that breaks down the most important news in the world of AI. You can sign up to receive this newsletter every week here.

Why OpenAI’s new open-weight models matter

OpenAI is opening up again.

The company’s release of two “open-weight” models—gpt-oss-120b and gpt-oss-20b—this month marks a major shift from its 2019 pivot away from transparency, when it began keeping its most advanced research under wraps after a breakthrough in model scaling and compute. Now, with GPT-5 on the horizon, OpenAI is signaling a return—at least in part—to its original ethos.

These new models come with all their internal weights exposed, meaning developers can inspect and fine-tune how they work. That doesn’t make them “open-source” in the strictest sens

See Full Page