GIMP is a free and open-source raster graphics editor used for image retouching and editing, free-form drawing, converting between different image formats, and more specialized tasks. GIMP is released under GPLv3+ licenses and is available for Linux, macOS, and Microsoft Windows

As a graphic designer for several years ago, GIMP is very recommended for a start-up designers who wants to understand the basics elements of design such as vectors, typograpy and colors management.

Inkscape is a free and open-source vector graphics editor. This software can be used to create or edit vector graphics such as illustrations, diagrams, line arts, charts, logos, business cards, book covers, icons, CD/DVD covers, and complex paintings.

According to my exprience Inkscape can work alternatively with Adobe Illustrator and it is more flexible to learn and saving a time in case you need to deal with vectors, texts, pictures, and icons in oder to create a certain designs

Adobe Illustrator is a vector graphics editor developed and marketed by Adobe Inc. Originally designed for the Apple Macintosh, development of Adobe Illustrator began in 1985. Along with Creative Cloud, Illustrator CC was released.

I've been using Illustrator more than 4 years, its really awesome for expert or beginners designer to create some advanced 2D designer, illustrations, and vectors. This work was designed for a coffee producing company to brand their product "Kivu Belt Coffee"

FreeCAD is a free and open-source general-purpose parametric 3D CAD modeler and a building information modeling software with finite-element-method support