DIFF is a good looking and easy to use diff tool. The diff view is generated by jsdifflib.

1. Paste in your base text and new text (2 files you want to compare).
2. Set the context size (number of lines above and below detected changes).
3. Click the SIDE BY SIDE button for a side-by-side comparison.
4. Click the INLINE button to see changes inline (in a single column).

Note: Leaving the context size blank will render the entire document. If you get excessive horizontal scrolling, adjust the context size to narrow down the view and/or click the "Expand" icon to go fullscreen.

replace
delete
insert