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

1. Enter the original code into first textarea element when the page loads.
2. Click on the Hide Original button to toggle to the second textarea element.
3. Enter the changed code into the second textarea element.
4. Click on the Show 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 the Hide ... button to hide the contents of the corresponding textarea element.
6. Click on the Show ... button to display the contents of the corresponding textarea element.