Open Weights
An open-weights model is one whose trained parameters are released publicly, so anyone can download, run, inspect, and fine-tune it. It's distinct from fully open source — the weights are open even when the training data and code aren't.
Also known as: open-weight model, open weights
“Open weights” means the model’s trained parameters — the numbers that actually encode what it learned — are published for anyone to download and use. You can run it on your own hardware, inspect it, and fine-tune it for your task, without a per-token dependency on a closed provider.
It’s distinct from “open source.” Fully open source would also release the training data and code; many “open” models release only the weights. That distinction matters for reproducibility and licensing, but for most builders the practical win is the same: open weights let you self-host, keep data in-house, and customize — the freedoms that make the open ecosystem a real alternative to proprietary frontier APIs.
