Virtual Serial Port (com0com alternative)

Virtual Serial Port Driver is basically a null-modem emulator (com0com) by Eltima Software.    The software is designed to create virtual serial ports and pair them. Two COM port based applications are thus connected via virtual bridge and can exchange data. Whatever data is sent from one end of the bridge is received in an instant by the application at the other end.

Null modem emulator creates ports in such a way that your applications won't even notice the difference between real and virtual ports. The app imitates all the settings, including baudrate, HandFlow control and supports all signal lines. Link between virtual serial ports is much faster than real null-modem cable connection and solely depends on your processor speed (average transfer speed is about 5.5 Mbytes/sec)

Com0com lists all virtual ports in PC's 'Device Manager', and they are accessible once the PC is turned on, before one logs in.
The application has a GUI version, and those who are going to build it in their own product can opt for a driver version with API.