git.eaglercraft.rip/eaglercraft/eaglercraft-1.8
However, it works by decompiling the minecraft 1.8 source code, and then applying patches to it, so it technically isn’t fully open source.
From the site:
It uses TeaVM and LAX1DUDE’s OpenGL emulator to run a Java virtual machine fully compatible with browsers.
TeaVm is an ahead of time compiler that outputs javascript and webassembly from java.
A few other things I really like about this project are how it downloads the files from an ipfs gateway, rather than hosting them, and how they use their own Gitea instance, rather than Github. Although they lose points for having a Discord, their opsec is much, much better than that of many other similar projects that are at risk of, or have been hit by a DMCA or other takedown request.