Where do you download the Unity headers for C dlls?

The manual states:

See IUnityInterface.h for the correct signatures. IUnityInterfaces is provided to the plugin to access
further Unity APIs.

Well great, where are they? There is no mention anywhere of the download location of these headers…
Does anyone know where they are hosted?

The header files for the pluginAPI is in the Unity folder. Usually at:

C:\Program Files\Unity\Editor\Data\PluginAPI\

On macOS it should be located at:


replace with the installed version of your Editor e.g.: 2019.2.15f1

Further down that manual page there’s a link to the Unity bitbucket repository, which contains a number of examples. e.g. https://bitbucket.org/Unity-Technologies/graphicsdemos/src/548c5251ddbe82129b2584992a0f50caa4c34c6c/NativeRenderingPlugin/PluginSource/source/Unity/IUnityInterface.h?at=default&fileviewer=file-view-default