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WebAssembly 3.0 with Andreas Rossberg

January 20, 2026·1 hr 4 min·4 clips

Rossberg explains why Siemens uses WebAssembly on embedded devices — not for performance, but to avoid rebuilding toolchains every time a new processor ships.

WebAssembly is presented as a project with a long memory. Andreas describes newer releases as extensions of ideas that were already in the design, even when the actual feature took years to land. The process is open, but it is not loose. Anyone can bring a proposal to the committee, at least in theory, but getting it accepted means convincing other people that the tradeoff is worth it. That matters for language implementers. The features sound less like a wish list and more like pressure building up from people trying to compile real languages into a portable runtime. A few surprises still show up. Relaxed SIMD is one of the 3.0 additions Andreas says he did not expect, and he does not sound thrilled about it. Other changes had been waiting in the background for longer. Larger address spaces, including 64-bit support, feel less like a turn in direction than something the designers knew WebAssembly would eventually need. Kevin keeps pulling the conversation back to architecture: how committees handle proposals, how language support catches up, and why these changes move slowly. The episode does not sell WebAssembly 3.0 as a neat breakthrough. It makes the release feel like the product of process, constraint, and a lot of delayed necessity. The ending turns to trust. Code may come from dubious sources more often now, but Andreas notes that human-written code can be dubious too. The problem is how quickly people accept AI suggestions compared with code from another person. Formal validation would help, but the answer stays measured. Checking generated code is useful, and still hard. That fits the episode: WebAssembly is alive, useful, and unfinished.

As heard by us

A grounded, developer-focused look at WebAssembly 3.0 as a standards story, not just a feature release.

WebAssembly 3.0 comes through as the next step in a long, deliberate standards effort, not a flashy platform reset. Andreas Rossberg traces how a low level target for C and C++ grew into a portable, secure runtime model used across browsers, edge compute, embedded systems, and…

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Why you'd press play

One of WebAssembly's founding architects takes you inside the design tradeoffs from 1.0 to garbage collection in 3.0.

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