OpenAI has released two open-weight language models that excel in advanced reasoning and are optimised to run on laptops with performance levels similar to its smaller proprietary reasoning models.

An open-weight language model’s trained parameters or weights are publicly accessible, which can be used by developers to analyse and fine-tune the model for specific tasks without requiring original training data.

“One of the things that is unique about open models is that people can run them locally. People can run them behind their own firewall, on their own infrastructure,” OpenAI co-founder Greg Brockman said in a press briefing.

Open-weight language models are different from open-source models, which provide access to the complete source code, training data and methodologies.

Separately, Amazon announced OpenAI’s open-weight models are now available on its Bedrock generative AI marketplace in Amazon Web Services. It marks the first time an OpenAI model has been offered on Bedrock, said Atul Deo, Bedrock’s director of product.

“OpenAI has been developing great models and we believe that these models are going to be great open-source options, or open-weight model options for customers,” said Deo, in an interview. He declined to discuss any contractual arrangements between AWS and OpenAI.

Amazon shares tumbled last week after the company reported slowing growth in its AWS unit, particularly compared with rivals.

Highly contested

The landscape of open-weight and open-source AI models has been highly contested this year. For a time, Meta’s Llama models were considered the best, but that changed earlier this year when China’s DeepSeek released a powerful and cost-effective reasoning model, while Meta struggled to deliver Llama 4.

The two new OpenAI models are the first open models OpenAI has released since GPT-2, which was released in 2019.

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OpenAI’s larger model, gpt-oss-120b, can run on a single GPU, and the second, gpt-oss-20b, is small enough to run directly on a PC, the company said.

OpenAI said the models have similar performance to its proprietary reasoning models called o3-mini and o4-mini, and especially excel at coding, competition maths and health-related queries.

The models were trained on a text-only dataset, which, in addition to general knowledge, focused on science, maths and coding knowledge. OpenAI did not release benchmarks comparing the open-weight models to competitors’ models such as the DeepSeek-R1 model. — Anna Tong and Greg Bensinger, (c) 2025 Reuters