Graphics / Photography / Video

Gimp http://www.gimp.org

Gimp – vs – Photoshop https://expertphotography.com/gimp-vs-photoshop/

Rawtherapee https://www.rawtherapee.com

like Camera RAW image converter and processing software

Like Photoshop-CS

Darktable http://www.darktable.org/

like Adobe lightroom

Krita https://krita.org/

like Corel Painter Adobe Photoshop

Inkscape https://inkscape.org

like: Adobe Illustrator; CorelDraw; Affinity Designer

Blender http://www.blender.org/

like Maya

Scribus https://www.scribus.net

like Quarkxpress; InDesign MS Publisher

Kdenlive https://kdenlive.org/

like Adobe Premiere Pro

OpenShot https://www.openshot.org

like Simple Video editing software

Handbrake https://handbrake.fr/

like video ripper and transcoder software

Music Studio Software

LMMS http://lmms.io/

Rosegarden https://www.rosegardenmusic.com/

Audacity https://www.audacityteam.org/

Frescobaldi http://www.frescobaldi.org/

MusicBrainz Picard https://picard.musicbrainz.org

Clementine http://www.clementine-player.org/

Office / Work / Science Education

WPS Office https://www.wps.com/en-US/

like MS Office

Liber Office http://www.libreoffice.org

like MS Office

Dia https://wiki.gnome.org/Apps/Dia/

like UML editor Ckt Diagram Ms Visio

Accounting / Book Keeping

GnuCash https://gnucash.org/ like quick books

Investing-Money Mgt

Portfolio Performance https://www.portfolio-performance.info/en/

Genetics

Biogenesis http://biogenesis.sourceforge.net/

Ugene https://ugene.unipro.ru