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.