Both Open MPI and OpenUCX are freely available. The Open MPI project is an open source, MPI-2 implementation, developed and maintained by a consortium of academics, researchers, and industry partners. OpenUCX is a collaboration between industry, laboratories, and academia to create an open-source production grade communication framework for data centric and high-performance applications.

You can find more information on the Open MPI and OpenUCX web pages, respectively.