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, announced a landmark return to its open-source origins.
The company unveiled two new open-weight language models, gpt-oss-120b and gpt-oss-20b, marking its first public release of freely available AI model weights since GPT-2 in 2019, long before the AI hype took over the tech world.
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Open-weight models enable anyone to download, examine, run, or fine-tune the LLM, and they eliminate the need to rely on remote cloud APIs or expose in-house sensitive data to external services.
OpenAI has not, however, released the training data used for these models because of legal and safety concerns. That will not please open-source AI purists, but developers worldwide are already putting the two models to the test.
This change contrasts with OpenAI’s approach over the past five years. The business has prioritized proprietary releases fueled by massive Microsoft investments and lucrative API deals.
After all, you can’t hope to become a trillion-dollar AI company without maximizing your profits. On the other hand, open source has consistently demonstrated that when code is developed openly, everyone, including the company that releases the code, benefits.
The gpt-oss-120b model targets high-performance servers and desktops with beefed-up specifications — 60 GB of VRAM and multiple GPUs — while the gpt-oss-20b version is compact enough for most laptops. You can download the models from Hugging Face or GitHub. In both cases, your hardware must run MacOS or Linux specifically, with MacOS 11 Big Sur or later, or Linux with Ubuntu 18.04 or later to run the programs. It could also work on Windows Subsystem for Linux (WSL) 2.0 on high-powered Windows systems.
OpenAI says, “The gpt-oss-120b model achieves near-parity with OpenAI o4-mini on core reasoning benchmarks, while running efficiently on a single 80 GB GPU. The gpt-oss-20b model delivers similar results to OpenAI o3‑mini on common benchmarks and can run on edge devices with just 16 GB of memory.”
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So, how good is it? AI expert Nate Jones has kicked its tires and reports, “This one is specifically aimed at retaking American dominance in open-source models now that Llama has dropped the ball. Early tests indicate a higher than usual risk of hallucination, but the power of the model is real and continues to underline how quickly AI is progressing. I’ll be watching for how quickly these models get picked up on Hugging Face by developers (who are hard to spin).”
The models are licensed under Apache 2.0, one of the most permissive open licenses. This enables enterprises and developers to use, modify, and monetize the technology without restrictive terms, unlike Meta’s not-really open-source Llama LLMs.
Both models employ a mixture-of-experts (MoE) architecture. This offers robust reasoning capabilities while being optimized for efficiency and tool usage. Programmers will be interested in its code execution capabilities, while writers and researchers will find its inclusion of web search as part of their thought process interesting. On the other hand, early reports show very high levels of hallucinations. Additionally, both models are limited to processing text.
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Why has OpenAI made this move? The company explicitly stated that these open releases aim to lower barriers in emerging markets and among smaller organizations.
The business has also noticed that the Chinese open-source DeepSeek, which was released in January and immediately made waves thanks to its speed, power, and the fact that it was open source. As Altman said shortly after DeepSeek caught everyone’s attention in a Reddit “Ask Me Anything,” he believes OpenAI has been “on the wrong side of history” about open-sourcing its software.
Now, on the eve of the ChatGPT 5 release, OpenAI is on history’s right side again.
