123D Circuits

http://blog.123dapp.com/2013/09/introducing-123d-circuits

Free circuit design Web app.

Here are some of the most compelling features:

  • Virtual breadboard based design, allowing to build and experiment with circuits just as you would in real life.
  • You can add an Arduino to your design, and edit the code right in your browser.
  • Real-time and interactive simulation of both your Arduino code and the circuit attached to it.
  • Full collaborative editing (think of Google Docs for electronics).
  • Powerful yet easy component editor, making it super easy to add new components to the shared library.