EaglercraftX-1.12-Server - If you are looking for the "Paper" aspect, Eaglercraft typically uses a BungeeCord/Velocity gateway to connect web clients to a standard Minecraft 1.12.2 server (like PaperMC).
https://github.com/lax1dude/eaglercraft-1.12 Compiled HTML/JS is in the stable/ folder. eaglercraft 112 2 github upd