An open-weight model is an AI model where the trained parameters (the weights) are publicly available to download and run.
In practice, this usually means you can:
- Run the model locally or on your own cloud.
- Avoid paying per-request API pricing to a hosted provider.
- Fine-tune or adapt the model for your own use cases.
However, open-weight does not always mean fully open source. Many open-weight releases do not include all of the following:
- Full training code.
- Complete training dataset details.
- A license that allows unrestricted study, modification, and redistribution.
That is why the distinction between open-weight and open-source matters.