Eaglercraft 1.12 Wasm Gc [work] May 2026

Eaglercraft had already pulled off the impossible: a full Java-to-JavaScript recompilation of the Minecraft client using TeaVM, plus a custom WebSocket-based multiplayer protocol. It ran in any modern browser, no installation needed. But version 1.12 was a beast — over 8 million lines of Minecraft code, plus the labyrinthine complexity of the 1.12.2 engine. Performance stuttered. Garbage collection froze the screen mid-PvP.

Alex recompiled the 1.12 client using a custom TeaVM fork targeting Wasm GC. Instead of outputting JavaScript heap management, every object allocation, every new BlockPos() , every HashMap of entities — all became Wasm GC structs and arrays, traced and collected by the browser’s optimized garbage collector. eaglercraft 1.12 wasm gc

Alex grinned. Eaglercraft 1.12 with Wasm GC wasn’t just a tech demo. It proved that full legacy Minecraft could live forever, directly in browsers, with near-native performance — no plugins, no downloads, no Java runtime. Eaglercraft had already pulled off the impossible: a

And the browser’s garbage collector just hummed along, quietly collecting fallen leaves in the background. Performance stuttered

The first test was a superflat world with 64 villagers. On the JS backend, frame rate dropped to 15 FPS with major GC spikes every 5 seconds. On Wasm GC? A steady 45 FPS. No visible hitches. The collector ran concurrently, reclaiming entire chunks of blocks and entity pathfinding data without stopping the world — in both senses.

But it wasn't magic. Wasm GC lacked finalizers, so native resources (like WebGL textures) still needed manual cleanup. The class hierarchy of Minecraft — TileEntity subclasses, IRecipe types — all required precise casting support. And the biggest hurdle: reflection. Minecraft 1.12’s ObfuscationReflectionHelper and dynamic proxies broke. Alex had to write a custom transformation pass at compile time to replace reflective calls with direct Wasm GC casts.

That night, the code was pushed to a public branch. Within days, players were running modded 1.12 worlds on school Chromebooks, fighting the Ender Dragon with zero lag spikes.