Text Compare is a free portable tool which detects and highlights the differences between two text files.

The program is surprisingly small (only just over 100KB), a single executable. There's no adware or other complications, just unzip, run it and go.

Text Compare's interface is a poorly designed, cluttered mess, but you'll still have it figured out within a minute or two, and pointed the program at the two files you'd like to compare. Each one is then displayed in a separate pane.

Clicking the "Compare and show all" button highlights the lines (not the characters) which are different in each file. An annoying pop-up dialog displays a summary of the results, and tells you if there's a difference in the file encoding. (This pop-up appears every time you do a compare, and must be cleared by clicking OK before you can continue.)

If a line has been inserted somewhere then Text Compare is smart enough to recognise that, and lines which have just been moved (line 4 is now line 5) are highlighted in a separate colour.

If your source files are lengthy, or the changes minimal, then you can optionally choose to view just the differences, the moved and copied files, or the new/ changed lines.

There's also a simple search tool, and you can open any file in its default Windows application with a click.

Version 1.0.2.2:
    - Command line support
    - Synchronised scrolling
    - Remember window state