Cooperative Advancements is a mod for Minecraft that automatically synchronizes advancement progress between all players in a multiplayer game. It works in both dedicated multiplayer and single player games opened to LAN.
I originally made this mod for personal usage in a mod pack I was making, where there were tons of advancements that would take way too long to collect by myself. I thought it would be fun to be able to work on progressing through these advancements with others, so this mod was born.
Download the mod on CurseForge or check out the source code on GitHub.