Inkscape

Inkscape is the standard open-source vector tool: paths, boolean ops, gradient meshes, trace bitmap, and a proper node editor, all built around SVG as the native format. Version 1.x brought huge performance gains and a dockable, customizable UI. For logos, icons, diagrams, and web graphics it does the job fully, and being SVG-native is actually an advantage for web work.

Where it falls short of Illustrator: CMYK/print workflows are weak (you’ll be exporting through Scribus or command-line tricks for press-ready output), AI file import is lossy, and very complex documents can get sluggish. Artboard support arrived late and is still rougher than Illustrator’s. For screen-destined vector work, though, there’s little reason to pay Adobe.