Webassembly just shipped its biggest spec update in years, quietly. release 3.0 landed september 8…
webassembly just shipped its biggest spec update in years, quietly. release 3.0 landed september 8 with multiple memories and typeful references, the features apps have needed since the browser days ended.
the sandbox is finally a general-purpose runtime.
Context
The WebAssembly site's post of September 17, 2025 announced Wasm 3.0 as the new live standard, with the title page reading Release 3.0, 2025-09-17. It lists multiple memories (a single module can declare several), typed references (reference types that describe the exact shape of the referenced heap value), 64-bit address space, GC, tail calls, exception handling, relaxed vector instructions, a deterministic profile, annotations and JS string builtins, and calls it a substantially larger update than 2.0, which was finished three years earlier.
The note says release 3.0 landed September 8. The first-party post is dated September 17, 2025, about a year before the note, and no September 8 event was found. The 2026 W3C pages are Candidate Recommendation Drafts of a living specification (the Core draft read is dated May 27, 2026), which the W3C text says the group intends to maintain in that state, so a draft status is distinct from release 3.0 being published. No browser or runtime support tables were inspected, so implementation status is not established. Quietly is the author's take.
Watch next
- A W3C step beyond Candidate Recommendation Draft, and runtime support tables.
Sources
Provenance
The note above is reproduced unedited from the original post, first published on Threads on 22 September 2026 at 01:47 IST. Sources are the papers and datasets the note draws on.
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