Can I use my laptop as a second monitor?

"Here's an interesting freeware solution:

ZoneScreen"

Maxivista is a commercial software that lets you do this.

"You can also do it via remote assistance, if you have a second output on your display adapter. I mean that you have to be able to hook another display to your desktop PC via cable. The remote assistant is able to show the secondary desktop (as well as the primary) even if the monitor is not physically hooked.

No third party programs required for this solution.

Edit: In details, if you have a multiple outputs in your display driver but no monitors (not hooked), you can do the following (works for nvidea quadro 2000 and win 7):

go to: nvidea control panel -> workstation -> view system topology
from there: (main display port) manage EDID... -> export EDID...
same place: (secondary display port) manage EDID... -> load EDID... (choose the file that you saved in the previous bullet)
Now you have a 'virtual' secondary screen and you can use remote assistant to zoom to it

This trick does not require admin rights nor extra software."

"You can use your laptop as second monitor using "" Real VNC "" Software. I have done many times you can operate by laptop or desktop anyone and you can see in other.

Update :

I misunderstood the Question. to use your laptop screen as the extended screen use Zone Screen for Windows 7 or lower versions.It is no longer developed. See the first answer."

"dmx.sourceforge.net - have to fool around before you can get it to work. But you can create video-walls with it. (or just two screens)
Example : buy a raspberry pi for 30$ and a hdmi screen for 140 $ ... no : buy 15. Put a HQ switch between all. install dmx (Distributed Multihead X Project) and you have a nice 7920x4320 desktop."