A Speckle connector for Open Cascade Technology will enhance software and data interoperability within the architecture, engineering, and construction industry. The project aims to bolster the use of free software in the sector, by uniting the capabilities of two open-source ecosystems in a sector where proprietary tools are currently very dominant. On the one hand, Speckle open-source connectors enable seamless collaboration across diverse AEC software; it ensures accurate and efficient collaborative workflows between various actors and disciplines, thus contributing to the freedom of choice of digital tools, avoiding a captive market. The connector's open-source design encourages community contributions, fostering continual improvement. On the other hand, Open Cascade Technology is an open-source geometric kernel. It is used in free software alternatives such as Freecad or Salome, and in open-source libraries such as IfcOpenShell, which allows the development of applications based on IFC, the open standard for Building Information Modeling. Also, the open-source nature of Open Cascade Technology enables many researchers and professionals to develop their own highly specialized digital tools. Our prototype would connect this ecosystem to all AEC industry software, via Speckle.