For a free, integrated solution, Solid Edge Community Edition defeats all open-source tools because it combines CAD editing with nesting in one interface.

Solid Edge 2D Nesting is a professional add-on module for Siemens Solid Edge designed to optimize material layouts for cutting. While the full 2D Nesting module is typically a paid add-on, you can access it for free through specific Siemens Free Software Offerings How to Access Solid Edge 2D Nesting for Free