The state of open-weight licensing, mapped

The Frontier Wire editors — Tue, 08 Sep 2026 00:00:00 GMT

"Open" has become the most overloaded word in AI. Model weights that anyone can download are described as open, and so are models released under terms that forbid certain uses, cap the size of the company that may use them, or reserve the right to revoke access. These are not the same thing, and the difference decides whether you can build a product on the model. This survey maps the licence families in use and what each permits.

The families

Family	Examples of terms	Commercial use	Restrictions on use	Open by the OSI definition
Permissive open source	Apache 2.0, MIT	Yes	None beyond attribution	Yes
Community licences	Vendor-written "community" terms	Yes, with conditions	Often a user-count threshold, naming rules, or a ban on training competing models	No
Responsible AI licences	RAIL and variants	Yes	A list of prohibited uses that travels with the model	No
Research-only	Non-commercial terms	No	Research and evaluation only	No
Custom terms of use	Vendor-specific	Varies	Varies; often includes acceptable-use policies that can change	No

Permissive open source

A minority of notable models ship under Apache 2.0 or MIT. These are the only licences in the table that meet the Open Source Definition: anyone may use, modify and redistribute the weights for any purpose. If you need certainty that your rights will not change, this is the family to build on.

Community licences

The most common terms on large, capable models are vendor-written licences that grant broad commercial use with specific carve-outs. The usual ones are a threshold on the licensee's monthly active users above which a separate licence is required, a requirement to display attribution, and a prohibition on using the model's outputs to improve other models. These licences are workable for most companies but are not open source, and the carve-outs are exactly where a legal review should focus.

Read the clause about training other models. It is the one most teams break without noticing.

Responsible AI licences

RAIL-style licences attach a use-based restriction list to the model: no use for surveillance, for generating disinformation, for certain medical claims, and so on. The intent is ethical, and the restrictions are ones most businesses would never approach. The practical problem is that use restrictions are incompatible with the open-source definition and are difficult for downstream projects to inherit cleanly.

Research-only and custom terms

Some releases are explicitly non-commercial. Others ship under terms of use that reference an acceptable-use policy hosted on the vendor's website, which the vendor may update. A model licensed this way can become unusable for your product without the weights changing at all.

What to do with this

Before building on any open-weight model, find the licence text, not the announcement, and answer four questions: Is commercial use allowed? Is there a size or user threshold? Can outputs be used to train other models? Can the terms change after download? The answers sort every model in this survey into one of the five families above, and that placement is more informative than any benchmark.