nprofile1qy2hwumn8ghj7un9d3shjtnddaehgu3wwp6kyqpqupkp7fd7rc3lrjg23r8gy0wc723vze7mxlx5984ut6zurjzpf5xsv56m2n (nprofile…6m2n) for example, i use this website to optimize SVGs https://jakearchibald.github.io/svgomg/
try visiting it, then turn off your network and refresh the page. still works! it'll even work if you open a new tab and type in the URL
i think service workers are actually *more* useful for static sites with no backend. they might not be that helpful for, say, a mastodon client (bc the HTTP requests to get and post toots still need the network). but that SVG tool doesn't make any requests so it works great offline