https://howerj.github.io/
https://howerj.github.io/libforth/libforth.htm
Although Embed is the more mature project than libforth.
I really liked having a full explanation line-by-line. If you're interested in Forth, JonesForth is another classic literate program: https://github.com/nornagon/jonesforth/blob/master/jonesfort...