Many large language models (LLMs) are described as open source, but
if one looks a bit deeper it turns out that is not actually so; the
model may be free to download, it may be "[open weight](https://opensource.org/ai/open-weights)", but it
does not fit the [Open Source
Initiative](http://opensource.org/) (OSI) [Open Source
Definition](https://opensource.org/osd) (OSD). Assessing the actual openness of models is not
easy, as Arnaud Le Hors explained in his talk about the [Model Openness Tool](https://mot.isitopen.ai/) (MOT) at [Open
Source Summit North America](https://events.linuxfoundation.org/open-source-summit-north-america/) 2026. The tool is designed to help
users of LLMs understand to what degree a model is (or is not) open, and to combat the openwashing that is prevalent with LLMs.
source & further reading
lwn.net — original article