Alternate Open source softwares

This is a really good website I came across while finding some free software for my personal use. Great thing about this website is that it hosts all software which are best alternates for frequently used software in windows operating system. OPEN SOURCE, if you have little knowledge about this term, do some googling and find out. The market is moving towards Open source now and there are lot good things to know about this terms...
See below the snap shot of open source software alreay in market and being used.

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