Open-Weight Model

Open-source AI

In one sentenceA model whose trained files are published, so anyone can download, run and customize it on their own computers.

What it means

Closed models (GPT, Claude, Gemini) are used through the company's app or API. Open-weight models (such as Meta's Llama, Mistral, DeepSeek and Qwen) can be downloaded and run privately.

"Open source" is often used loosely; many open models share the weights but not the training data.

How to use it

• Relevant when privacy, cost at scale, or customization matters enough to justify running your own infrastructure.

Related terms

Model Foundation Model Fine-Tuning