Maya Mansur-Rig is a free modular rig builder for characters

First released in 2021 and regularly updated, Mansur-Rig is an "advanced modular rig builder" for Maya, built on a custom C++ node library. It allows the creation of joint-based full-body and facial rigs for human and humanoid characters, although it is not an auto-skinning tool. Key advantages, as highlighted in the online FAQ, include high performance of generated rigs, a flexible non-linear workflow, and the ability to create rigs for models that are not in a T-pose.

Among other notable features are a ready-to-use user interface for animation selection and the LODs Tool for managing transitions between character detail levels.
In the new version, Mansur-Rig 2.5, an online library of character and vehicle rigs has been added, which is also available for free. The software comes with a detailed user manual and video tutorials. Mansur-Rig can now be downloaded for free, but installation requires registering an account on the product's website, as shown in the video above. The software is licensed for use in commercial projects, and you can even sell rigs created with it, though users also need Mansur-Rig to use these rigs. However, animations created with Mansur-Rig can be exported from Maya in FBX format, for example, for use in game engines.

According to the developer, making the software free "by no means signifies the end of development and support." "We hope this change will encourage the community to use Mansur-Rig more, leading to more bugs being found and fixed, and new needs being identified and addressed." You can view the features under development on the Mansur-Rig Trello page.

Mansur-Rig 2.5 is compatible with Maya 2018 and later on Windows and Linux. It requires the PyMEL module, which was included by default in older versions of Maya but now needs to be installed separately; details can be found in the online documentation. The software is currently free, including for use in commercial projects. You can also sell character rigs created with Mansur-Rig.