1. websocketify allows binary, while websocketd is text-only
2. websocketify does I/O through a socket that the program uses (and that it sniffes through rebind.so), while websocketd relies on stdin / stdout
3. The arguments are different
websocketd --port=8080 my-program
websocketify 8080 -D -- my-program
Also, not sure if websocketify can but websocketd also has --dir argument and can supervise and route many sockets to many different programs.