Recently, after my fun with Arduino Starter Kit I have looked for online, cloud-based Arduino editor/simulator.
In the past I heard about codebender.cc, but now it is changing and new registrations are disabled.
Alternatives Which I found are:
Good feature would be to make it possible to embed project on Instructables.com and other sites.
So, I decided to try circuits.io, what I'll describe below.
All the pics are animated gifs, demonstrating each step - step by step;)
If You don't see the animation, check Your browser settings
Step 1: Sign Up/Sign In
The first step is to Sign In.
It is possible Sign In with Facebook account. I have created new account (Sign up).
After that we'll see the main page and start to work...
Step 2: Create New Project
On the top right side click the big plus sign and select New Electronic Lab.
Now You can see the workbench.
Step 3: Add Components and Wires
In the workbench we can build our circuits by adding components and connecting it.
There are available various components from the basic electronic components like resistors, capacitors, etc to breadboard and programmable components like Arduino.
On the top bar, after switching editor to another view is possible to edit schematic or PCB. The default view is breadboard.
Step 4: Write the Code & Simulate
The next step is writing the program for Arduino.
Code editor is available at the bottom, after click to Code Editor Button;) During writing code, You can simulate the circuit (by clicking Upload & Run).
Standard Arduino tools, like Serial Monitor are available. Debugger is available too.
Step 5: Embed It!
We can share our project by embedding it to our website, blog, etc.
I'll show how to do it on the example of Instructables.com.
Click Show more button on the top and select Share & Embed. Now copy the html code and paste to the website (in source) where you want to show the project.
Live example of how it works You can see in my another Instructable.