Concept · Building with AI

Open source vs open weights

Also called: open weights, open-weight, open weight model, open-weights model, open model, open models, open source AI, open source model, closed model, closed models, proprietary model, closed source model, closed weights

Two labels for AI models that people often mix up. Open weights means the trained numbers of a model are published, so anyone can download and run it. Open source AI, as the Open Source Initiative defines it, asks for more: the weights, the code used to train and run the model, and detailed information about the training data, on terms that let anyone use, study, change and share the system. A closed or proprietary model publishes none of these, and people reach it only through its maker's app or API.

For example: A lab releases a model's weights but not its training code or a description of its data. Under the Open Source Initiative's definition that model is open weights and is not open source AI. A team that wants to run a model on its own hardware needs at least the weights.

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