EasyEDA. It is a free web-based tool for schematic capture, PCB layout, and circuit simulation. The best part of any cloud- or web-based development tool is that it runs on a remote server (no worries to install on local machines), always up to date, and is accessible from anywhere through internet. EasyEDA is a zero-install cloud-based EDA application; all you need is a web-browser and internet connection and you are ready to draw circuits, run SPICE simulation, design PCBs, and even place an order for fabricating PCBs. I have a very pleasant learning experience playing with it for a couple weeks and I found the learning curve wasn?t too steep.