Compare It! 

This application is designed to detect and highlight differences between two text files in various formats. It supports documents that contain code written in programming languages like C++, Java, C#, Delphi, HTML, etc. This tool is useful for programmers and software testers, as it will help them easily find syntax errors and bugs in their code.

Compare It offers an easy way to load the files that you need to compare. Its main window consists of two panes, one for each file, which will display text content by using different colors for differences and similarities. Compare It can also handle documents created with Microsoft Office (DOC, RTF, XLS, etc.) and even PDF files. It offers access to a lot of settings enabling you to set up various file filters, customize interface colors, assign keyboard shorcuts, etc.

I think that Compare It is worth its price. It run smoothly and helps you easily find similarities and differences between various files. Moreover, it is a multi-platform application, which runs even on Mac and Linux systems.