For very rough prototypes, a XAMPP localhost with plain HTML, CSS, and JavaScript; ready to go in about 10 seconds. The bottleneck then becomes how fast you ca

For very rough prototypes, a XAMPP localhost with plain HTML, CSS, and JavaScript; ready to go in about 10 seconds. The bottleneck then becomes how fast you can "Ctrl+S, Alt+Tab, Ctrl+R" (or insert a 1 second refresh meta tag on a split screen and "Ctrl+S" only...but after a while even a 1 second refresh starts to feel slow).