WebForge is a port of Minecraft 1.6.4 forge to the web browser. It can load simple mods, such as this, but also more complex ones such as the Aether II.
To compile the offline download: run python3 bundleforofflinedownload.py. Download the precompiled offline download from the Releases section.
Yep, that's all I have to say. Words can't explain what a demo can! Play it here.
Join the Discord server.
Navigate to the src/wssproxy directory. Run javac WssProxy.java, then run java WssProxy <server ip> <server port> <wss port, optional>. It will tell you the wss:// ip (put that in WebForge WITHOUT the wss://) and a https:// website that you should visit in your browser before connecting to the server in WebForge.
This will eventually change, multiplayer is still in testing.