#2 LibreOffice:
Developed by The Document Foundation, LibreOffice is a free and open source office suite that works using OpenOffice as the core. The office suite was initially designed to be compatible with other major office suites, including Microsoft Office. LibreOffice is right now available a number of platforms like Microsoft Windows, Linux and Mac OS X. The software is written in C++ and Java.

LibreOffice offers six applications in their suite namely, Writer, Calc, Impress, Draw, Base and Math.

#3 Gimp:
Gimp is short form for GNU Manipulation Program. Gimp is an image retouching and editing tool, released and licensed under the GPLv3 as free and open-source software. The software is considered as a major open source rival for Adobe Photoshop. Although the software holds sheer similarities with Photoshop, still Gimp is a major player in the open source market. The software is available across various platforms such as Windows, Mac OS and Linux.

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