This section describes the ARToolkit SDK for augmented reality development (http://artoolkit.org/). If you don't want to use ARToolkit, you can skip this section.
ARToolkit is an open source software project. It is free to use both for the development and the distribution of your apps that use it. Unlike Vuforia, there are no license fees. As an open source project, the source code is available to anyone who wants to use it, read it, and even extend it. ARToolkit is owned by DAQRI, a prominent AR industry leader, and is free to use under a LGPL v3.0 license (see http://archive.artoolkit.org/artoolkit-licensing).
If you distribute an app built with ARToolkit, it needs to include an acknowledgement and license notice, for example, in an about box. ARToolkit has the distinction of being perhaps the first and continuously supported open source AR SDK...