This page allows you to find the differences between two blocks of plain text. Simply paste your text into the two small boxes on the left-hand side (#1 and #2) and hit the Compare Text button. You may have to scroll down to see the controls again after the first set of results is generated. Switch between comparing whole lines, words and characters until you obtain the desired results.
Using this site is free, but a voluntary donation from you will help keep it going, able to cope with large diffs and increasing traffic.
We have many features not found in other online compare text tools, such as detecting re-ordered lines, omitting unchanged lines, navigation from one difference to the next and keeping your text secure from eavesdropping via https/SSL. No temporary files are created during the comparison process. Everything is done in memory.
P.S. We also produce software to directly compare two Microsoft Excel spreadsheets.