Mihai Parparita's Infinite Mac presents classic Apple operating systems (Mac OS 8, System 7) in the browser: "They boot instantly, are filled with useful programs, allow data import, export and persistence, and try to bring the best of the web to retrocomputing."
An abstract—and technical details—are offered in a blog post on Parparita's website.
It's a golden age of emulation. Between increasing CPU power, WebAssembly, and retrocomputing being so popular The New York Times is covering it, it's never been easier to relive your 80s/90s/2000s nostalgia. Projects like v86 make it easy to run your chosen old operating system in the browser. My heritage being of the classic Mac line, I was curious what the easiest to use emulation option was in the modern era. I had earlier experimented with Basilisk II, which worked well enough, but it was rather annoying to set up, as far as gathering a ROM, a boot image, messing with configuration files, etc. As far as I could tell, that was still the state of the art, at least if you were targeting late era 68K Mac emulation.
A demo is embedded below.