WebAssembly 3.0 becomes the new standard: 64-bit memory, garbage collection, exceptions

2025-09-17 · Publisher : W3C WebAssembly · Domain : Cloud & DevOps

On 17 September 2025, version 3.0 of the WebAssembly specification is published as the new standard: 64-bit address space, multiple memories, garbage collection, typed references, tail calls and exceptions.

### Background On 17 September 2025, the W3C WebAssembly Community Group and Working Group publish **version 3.0** of the specification, presented as the new "live" standard. The release folds in several long-proposed features that widen the bytecode's range of use beyond the browser. ### Key facts - **64-bit address space**: memories and tables can use `i64` as their address type, raising the theoretical limit from 4 GB to 16 exabytes. - **Multiple memories**: a module can declare and access several memory objects, easing static linking. - **Garbage collection** (GC): struct and array types managed automatically by the runtime, useful for managed-memory languages. - **Typed references**, **tail calls** (without consuming stack) and **native exception handling**. - Relaxed vector instructions (SIMD) and a deterministic profile, designed for replayable systems such as blockchains. ### Why it matters With garbage collection and exceptions, managed-memory languages can target WebAssembly without shipping their own memory manager, and 64 bits open the door to more memory-hungry workloads. For platform teams, it is a maturity milestone for the Wasm specification, to follow for server-side and edge uses; the standard says nothing about production adoption. Tail calls and typed references notably allow safe indirect function calls through the `call_ref` instruction. A custom annotation syntax also enriches the text format. ### Takeaway WebAssembly 3.0 brings into the standard the features missing for managed languages and large-memory workloads.

Tags : WebAssembly, Cloud natif, Edge, Open Source