Open Weight doesn’t just mean access to the model weights. The distribution terms of Open Weight models, which do not require distribution of source such as training data used to produce the weights, must comply with the following criteria:
The license shall not restrict any party from selling or giving away the weights as a component of an aggregate distribution containing components from several different sources. The license shall not require a royalty or other fee for such sale.
The product must include the weights, and must allow distribution of the weights. Where some form of a product is not distributed with the weights, there must be a well-publicized means of obtaining the weights for no more than a reasonable reproduction cost, preferably downloading via the Internet without charge. The weights must be the actual form in which a practitioner would use the weights. Deliberately obfuscated weights are not allowed. Intermediate forms such as training checkpoints or partial states are not allowed. Transformed versions such as quantized or optimized forms are only allowed if clearly distinguished.
The license must allow modifications and derived works, and must allow them to be distributed under the same terms as the license of the original weights.
The license must explicitly permit the distribution of weights derived from modifications. The license may require derived works to carry a different name or version number from the original weights.
The license must not discriminate against any person or group of persons.
The license must not restrict anyone from making use of the weights in a specific field of endeavor. For example, it may not restrict the weights from being used in a business, or from being used for genetic research.
The rights attached to the weights must apply to all to whom the weights are redistributed without the need for execution of an additional license by those parties.
The rights attached to the weights must not depend on the weights being part of a particular distribution. If the weights are extracted from that distribution and used or distributed within the terms of their license, all parties to whom the weights are redistributed should have the same rights as those that are granted in conjunction with the original distribution.
The license must not place restrictions on other components that are distributed along with the weights. For example, the license must not insist that all other models distributed on the same medium must be Open Weight.
No provision of the license may be predicated on any individual technology or style of interface.
The Open Weight Definition was originally based on the Open Source Definition, which was derived from the Debian Free Software Guidelines (DFSG).
Version 0.3, last modified, 2025-01-21