This app is a SPICE circuit file (cir, sp..) viewer, simulator based Ngspice software for your browser. 
It allows you to simulate the SPICE file directly on your browser.

This app supports basic circuits including voltage and current sources, resistors, capacitors, inductors, diodes, bipolar junction transistors, and ideal voltage-controlled switches.

This app only works locally without going through the server. It allows you to simulate circuit file instantly, real-time.
You can choose a SPICE file to simulate from your computer or from Google Drive™.
It has a very straight forward user interface that can get you started in seconds.