These top 20 open source freewares for productivity are alternatives to their respect commercial softwares but the quality are professional as commercial softwares.
LibreOffice / OpenOffice - Alternative to Microsoft Office
LibreOffice is a variant of OpenOffice. LibreOffice becomes popular nowadays.
GIMP - Alternative to Adobe PhotoShop
Powerful image manipulate tools with many useful functionalities.
Create Stunning Videos
Blender - Alternative to Maya
Blender becomes the alternative standard of 3D design.
Inkscape is a vector drawing software could handle fine curves and illustration.
Scribus - Alternative to commercial desktop publilshing softwares.
Audacity is a sound editor coulld handle .wav .mp3 .flac etc. found files and could record sound from microphone and lookback device.
Fast Stone Image Viewer - Alternative to commercial ACDsee viewer
FastStone Image Viewer could manage tons of images and could batch process resize, rename and watermark etc.
LMMS is a music create software based on powerful PC/laptop processor and equipments.
Simple Sitcky Note
Simple Sticky Note is an alternative to 3M Post-It notes software.
Firefox is a free and open source internet browser marks as top 2 desktop browser in the world.
Chrome / Chromium
Chrome is top 1 used internet browser in the world.