Memory64, Multiple Memories and Other Proposals

i64 addresses, memories > 4 GiB ((memory i64 1)). Useful for big data/ML. May be slower (bounds checks).

Multiple memories Several memories per module (i32.load 1...), for isolating data, merging modules, and secure buffers Extended constant expressions

i32.add/mul in global initializers (helps dynamic linking) JS String Builtins

Fast JS string operations imported from wasm:js-string Branch hinting Shipped (some engines)

@metadata.code.branch_hint custom section for likely/unlikely branches Custom page sizes

Pages smaller than 64 KiB (embedded devices) Wide arithmetic

128-bit multiply/add (i64.mul_wide_s) for crypto/bignums Shared-everything threads

Shared globals/tables/GC objects across threads, thread-local storage Stack switching Coroutines/effect handlers (Module 25)

ESM integration / source phase imports Import Wasm as ES modules

Compact import section, compilation hints, profiles Startup and size improvements

Custom annotations in WAT ((@name...)) Flexible vectors

Track: github.com/WebAssembly/proposals, the webassembly.org/features support table.