Long ago I fell in love with troubleshooting html code in a little free program called Notepad++. It has an awesome feature that allows you to compare and highlight changes in code or even text files. That’s right you can feed it two text documents and highlight all the differences between the files. This is great for spotting the code changes in a production file and a backup file. It also did the trick nicely to show me the differences in two csv files.
Notepad++ FTW! You can grab the installation files here. Notepad++ is a free notepad replacement application. It numbers lines and has plug-ins that extend its capabilities. All in all this is an awesome application!