The "About" from the Github source - https://github.com/edgcpp/compiler
The EDG C/C++ front end is the primary focus of this repository. The EDG front end is known for: its excellent parsing compatibility and bug emulation, to make sure source that compiles with Clang, GCC, and MSVC compiles with EDG; extensive documentation, to assist with development and modification; and extreme configurability, to allow it to be derived for use into a large number of C/C++ oriented products.
The compiler project also includes: a C-generating back end, which can be used to generate C code for C++ programs; a C++-generating back end, which is useful for source-to-source transformation applications; a prelinker, which handles automatic template instantiation; a minimal runtime support library (but not any "real" libraries, e.g., for stream I/O); utilities to write the intermediate language to a file, read it back in, and display it in human-readable form; a name demangler; and a collection of purpose built development tools.
From "The C++ Front End" - https://www.edg.com/c
The C++ front end supports the ISO/IEC 14882 standard. The C++17, C++14, C++11, and C++98/03 versions of the language are fully supported. Work is under way to support the C++20 language features (see our description of language features).
Under control of command-line options, the front end also supports ANSI/ISO C (both C89 and C99, and the Embedded C TR), the Microsoft dialects of C and C++ (including C++/CLI), GNU C and C++, Clang C and C++, Sun C++, the cfront 2.1 and 3.0.n dialects of C++, and K&R/pcc C.
That last bit is out of date (we didn't work much on keeping the web site up-to-date): The front end is mostly C++23-complete (modules notably lagging), and we have several C++26 feature in as well.
That is great! Thanks for the Update.
Just for others: Again from https://www.edg.com/c
The internal documentation comprises about 600 pages. The "External Interface" chapter of that document, covering command-line options, language dialect issues, and the use of language features like templates, is freely available for downloading in PDF format - https://www.edg.com/docs/edg_cpp.pdf (dated Nov 21, 2025 and hence presumably the latest version)
PS: Maybe these essential info (pointed out in my comments and updated by you) should be front and center in the new edgcpp website.