This site allows you to run ngspice simulations from a web browser environment. Whether you are using a Windows, Linux, or Mac computer, a smart phone, or a tablet, you always should be able to run a SPICE simulation! For more information about SPICE see the following links:
Check out the Example Circuits and the FAQ to get started.
See the Book Review section for helpful references or visit the Blog for information on updates to this site.
Read the Documentation or see additional SPICE related Links
Also try iVerilog.com for an online Verilog simulator