An SVG (Scalable Vector Graphics) editing program. For Inkscape versions up to 0.92.x, use -e instead of -o. More information: https://inkscape.org.
inkscape path/to/filename.svg
inkscape path/to/filename.svg -o path/to/filename.png
inkscape path/to/filename.svg -o path/to/filename.png -w 600 -h 400
inkscape path/to/filename.svg -o path/to/filename.png -D
inkscape path/to/filename.svg -i id -o object.png
inkscape path/to/filename.svg -o path/to/filename.pdf --export-text-to-path
inkscape path/to/filename.svg --select=path123 --verb="EditDuplicate;ObjectRotate90;FileSave;FileQuit"