RaphiMC

ViaVersion addon to add support for some notable Minecraft snapshots.

Minecraft Fabric mod which allows you to join EVERY Minecraft server version (Classic, Alpha, Beta, Release, April Fools, Bedrock)

Open source minecraft authentication protocol for proxies

A BungeeCord plugin to fix compatibility issues with ViaProxy, enabling seamless multi-version support for backend servers with reduced overhead.

Speed up immediate mode rendering in Minecraft