Synergy 2 vs. Multiplicity

A few weeks ago I mentioned how impressed I was by Multiplicity, a program that lets you seamlessly control two or more computers with a single keyboard and mouse — when you drag the mouse off the screen of one computer, you’re suddenly controlling the other computer. Very cool.

It turns out there is an open source solution for this sort of control as well, Synergy 2. In installed Synergy 2 on my computers at home and gave it a whirl, and the bottom line is that both programs are impressive but neither quite gets it right with the features that this sort of program needs.

Both programs do a very good job of letting you control more than one computer; the main difference between the two comes down to configuration, platform, security issues and costs.


Synergy 2 wins hands-down here since it is free. Multiplicity is $39.95 to $69.95 per machine depending on which version is purchased (the $69.95 version allows easier file copy operations between the various machines being controlled by the program). The cost of Multiplicity can really start to add up if you want to control 5 or 6 machines.


Multiplicity is the clear winner here. I had it up and running on my two machines in less than 5 minutes after I downloaded the software. With Synergy 2, the same process took 20-30 minutes with repeated references back to the documentation. At the moment, Synergy 2 is not something casual computer users would find easy to install. Of course, since controlling multiple computers with one keyboard/mouse is not something casual computer users are likely to want to do either, this may not be that big of an issue.


Both Multiplicity and Synergy 2 are missing a fundamental component of network security — neither program encrypts the TCP/IP traffic back and forth between the host machine and the machines being controlled. The Synergy 2 website says that is a feature that is being considered for a future release, while Multiplicity does not mention encryption at all on its site.

However, Multiplicity currently has a better security setup. It allows machines to be password protected, whereas Synergy 2 will simply allow you to connect to machines it finds running the software on the network. Similarly, Multiplicity allows the user to restrict access only to requests coming from a given subnet — that’s a feature I really appreciated.

But in the end both could use additional security option for the (rightfully) paranoid among us.


This is another area where the $40-$70 Multiplicity cannot come close to what Synergy 2 offers. Synergy 2 has clients for the following platforms:

  • Microsoft Windows: 95/98/Me/NT/2000/XP
  • Macintosh: OS X 10.2+
  • Unix: X Windows v.11r4+ and XTEST

Some of those are more stable and bug-free than others, but they’re all there in some form and being worked on.

Here’s what Multiplicity currently supports:

  • Microsoft Windows: XP, 2000, 2003

Ugh. And there are further restrictions for the host machine which cannot run, for example, on the 64-bit version of XP, though a secondary machine can.

Multiplicity’s website says an OS X client is in development, but says nothing about whether or not a Linux version is also being considered.

Personally, I’m waiting for the OS X client for Multiplicity to come out. If it performs as well as the XP version, I’ll probably buy it and install it on machines even given the high price. But if I was even considering a Linux box, I’d save my money and go with Synergy 2.

2 thoughts on “Synergy 2 vs. Multiplicity”

  1. Input Director is another interesting software solution I’ve been using for the past couple of years. Freely available as well. The new version I downloaded today resolved some flakiness with copy and pasting images between workstations.

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