Eaglercraft 1.21 represents the community's latest push to bring modern Minecraft features (like Trial Chambers and the Breeze) into a browser-playable format. While standard Eaglercraft officially supports versions like 1.5.2 and 1.8.8, recent community projects have successfully ported 1.21 content using specialized tools.
The most popular method to get a 1.21 feel in your browser is using a running ViaVersion and ViaBackwards . eaglercraft 1.21
: Many "1.21 servers" currently accessible via Eaglercraft utilize software like ViaVersion ViaBackwards Eaglercraft 1