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Closed Source

Closed source refers to technology whose internal source code is not publicly available for inspection, modification, or redistribution. In AI, the label can also apply when model weights, training data, architecture details, or evaluation methods remain controlled by the provider. Users may access the system through an application or API while depending on the vendor for updates, pricing, security fixes, and continued availability. Closed-source models can offer convenient managed infrastructure and proprietary capabilities, but they provide less transparency and portability. The term should be used precisely because a product may expose some documentation or code while keeping its central model and training process private.