Enfasten is a tool written in Go which takes in a static site, scales the images down to a number of different sizes, then rewrites all of your HTML to use responsive image tags with srcset attributes. It can also run all of your images through an optimizer like ImageOptim. This makes your static site faster for people to load because their browser can load the best image for their screen size and resolution, and it's backwards compatible with older browsers.I wrote this because on my site I frequently include images which are absurd sizes, such as a 2146x1258 screenshot from a high-DPI display. The user's browser downloads this huge image and promptly resizes it down to fit in my 660px wide blog. This is especially bad when people without high-DPI displays visit my site, but I still want things to look nice on high-DPI displays. The fact that I don't always remember to optimize my images makes this waste even worse.