Online circuit simulators

Spice simulators on the web:

http://www.falstad.com/circuit/. Uses javascript,no need for Internet connection,after site is loaded

https://www.circuitlab.com/editor/. Has chrome app for off line use (https://chrome.google.com/webstore/search/circuitlab?hl=en-US)

https://www.multisim.com/create/. Internet required for opening of the site, not for schematic and simulation.

http://www.partsim.com/simulator. PartSim is a free and easy to use circuit simulator that runs in your web browser.