This diff viewer overlays text and code so you can visualise the similarities and differences between the two sets.

1. Enter the original code into first textarea element when the page loads.
2. Click on theHide Original button to toggle to the second textarea element.
3. Enter the changed code into the second textarea element.
4. Click on theShow Original button to toggle back to the first textarea element.

The code in blue colour is the original code, and the code in red colour is the changed or altered code.The code in magenta is the overlap between the two sets of code.

5. Click on theHide ... button to hide the contents of the corresponding textarea element.
6. Click on theShow ... button to display the contents of the corresponding textarea element.