The Saxon-Forms implementation is a XForms prototype written using Interactive XSLT 3.0. Interactive XSLT 3.0 is a feature of Saxon-JS, which is an XSLT 3.0 run-time written in pure JavaScript for use in the browser or a platform that supports JavaScript.
See conference papers below:
Implementing XForms using interactive XSLT 3.0. XML Prague 2018.
Distributing XSLT Processing between Client and Server. XML London 2017.
The latest builds of Saxon-Forms is placed in the builds directory (i.e. saxon-xforms.sef.xml). However to build the tool yourself you will need Saxon-EE to export the stylesheet into an export file (SEF file) to run directly in Saxon-JS. See instructions to build the Saxon executable for Saxon-JS see: Exporting for JS
Saxon-Forms currently supports Saxon-JS 1.1.0. To run Saxon-Forms you will need the latest Saxon-JS which can be downloaded at Saxon-JS. Please see sample1 and sample2 which show two alternative ways to use Saxon-Forms.