Meld it’s small diff and merge tool (less than 1 MB) from Stephen Kennedy. These applications are assigned for visual identification differences in files, folders and merge them if it’s required.

Visually interface of Meld is ascetical – means that there are only the most necessary functions available in the main window: file, edit, settings and help sections.
There are a few indispensable buttons to make work with the program faster and helpful as it’s possible:
•   New comparison – dialog to choose objects for comparison either files or directories (you are able to open more than two files or directories and edit them in place dynamically);
•   Save – possibility to save comparison results then use it for your needs (edit, print etc.);
•  Redo and Undo – buttons to discard or return changes in comparison results;
•   Cursors Up and Down – allows to moving up and down between differences to make view and work with changes easier and demonstrable;
•   Stop – button to stop comparison.
So there are no difficulties also for inexperienced user to start working with this program. Besides basically features of file and directory comparison Meld has very useful feature: browse and view a working copy from popular version control systems such as CVS, Subversion, Bazaarng and Mercurial etc.
Also one of advantages is full i18n support it means that Meld adapted to different languages and regional differences - 18 stands for the number of letters are available to work with: bg, ca, cs, de, en_CA, en_GB, es, fr, hu, it, ja, ko, ne, nl, pa, pt, pt_BR, ru, rw, sr, sr@Latn, sv, vi, zh_CN, zh_TW. It’s very helpful because one of the problems of similar software is impossibility to work with international characters correctly.
      Meld is published by GPL license so it’s absolutely free. Currently this application is available for Linux and Mac platforms.