The best Virtual Null Modem Emulators

Olga Weis

Need to test your own serial app but have no free COM ports in your system? No worries, with a dedicated software you’ll be able to create as many virtual serial interfaces as you need. Even better, a decent software virtual port driver will help you establish a connection between your virtual COM ports using a virtual null-modem cable.

Probably the most important thing for any user is to choose a solution optimally suited to their needs. Considering that there is a plenty of software tools serving for serial port emulation, in this article we will provide a short overview of the most popular null-modem emulators.


  1. Null-Modem Emulator by Eltima
  2. Com0com
  3. Virtual Null Modem by AGG Software
  4. Free Virtual Serial Ports

Null Modem Emulator by Eltima

Designed to create virtual COM port pairs, the software solution by Eltima is considered to be one of the most efficient virtual null modem emulators available today. Null Modem Emulator is aimed at creating an unlimited number of COM port pairs communicating via virtual null modem connections. Written to one port, serial data immediately appears on the other end of the port pair and vice versa. The software is particularly helpful for GPS data replication, capture and reproduction of serial port data, system debugging, and many other usage scenarios. The virtual ports created by this virtual null modem software are recognized by your operating system or any Windows app as real COM ports, so whether you need to test or debug your own data sniffer program, a serial device driver or firmware, there will be no shortage of virtual COM ports emulating all the serial port functionality.

Virtual Null Modem Emulator


If you like the idea of using a serial port simulator but are not sure which solution to choose, an open source kernel-mode virtual serial port driver com0com will definitely be a good choice. The program is able to provide a COM interface for device emulation apps. What this means in practice is that a device emulation program connects to one port of a serial port pair while the other port is used by Windows app (that needs to talk to the device). This way, for example, you can share faxes over IP. All you need to do is connect Windows Fax application to t38modem via virtual COM port pair. Com0com support for Windows 10 is another advantage of the app.

See comparison chart of Virtual Serial Port Driver and Null-Modem Emulator


Virtual Null Modem by AGG Software

Still trying to find an efficient null modem emulator? Easy-to-use Virtual Null Modem by AGG is designed to help you resolve any serial communication issue. The solution offers high hardware and software reliability (drivers are tested with the verifier under Windows XP SP2), fast connections via virtual null modem cable, full independence of virtual COM ports form hardware serial interfaces available in the system, and support for WDM, WMI, Power Management, PNP, etc.

Virtual Null Modem by AGG Software

Free Virtual Serial Ports

Ever wished you could emulate custom plug-and-play COM ports and I/O ports interfaced by 16550 UART? Well, that’s what Free Virtual Serial Ports solution is focused on. This free null modem emulator lets you create a virtual copy of a hardware null-modem cable with DB-25 or DE-9 connectors. The program lets two RS-232 DTE devices communicate with each other without using modems or any other DCEs. More than that, the app works exclusively in user-mode which ensures the stability of its performance.

Free Virtual Serial Ports

After comparing the functionality of all the aforementioned software tools, you can see that Virtual Null Modem Emulator by Eltima stands out for its versatility and ease of use. Such advantages as clean and friendly interface, efficient customer support, high level of data protection, possibility to create and remove virtual ports in real-time, etc. make Eltima’s solution an extremely effective tool able to cover a great variety of port emulation needs.

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Virtual Serial Port Driver

Requires: Available on Windows , 5.46MB size
Version 9.0.567 (5th Aug, 2017) Release notes