The latest Bifrost 2.14.0.0 includes a new Modular Rigging Framework.
The Bifrost Rigging Module Framework is a modular, compound-based system for building character rigs in Bifrost. It provides a flexible structure and data types for assembling individual rig parts into complete, production-ready rigs.
A module is a self-contained rig part that encapsulates both the structure and the behavior for a specific part of a rig. You can create your own custom modules by starting with the template_module, which serves as a foundation for building rigging modules tailored to your needs.
Bifrost rigging modules are fully integrated with Maya, allowing you to connect and interact with module inputs and outputs directly from the Maya scene. The Bifrost Rigging menu in Maya's Rigging menu set makes it easy to author procedural rigs in Bifrost and convert them into native Maya controls, joints, and attributes. In addition, you can control rigging module nodes from Maya, including enabling or disabling terminal flags and toggling optimization settings. A bifrostRigging command is also available for more technical users, allowing you to use the same features through scripted workflows or custom tools.
Note that the new Rigging Module Framework is not compatible with earlier, experimental versions.
Remember that you can always download the latest version of Bifrost by visiting the Autodesk Accounts Portal.