WASI 0.3 shipped on June 12, 2026, expanding the interface with sockets and filesystem modules.
The release adds the "wasi:sockets" and "wasi:filesystem" preview APIs, plus stabilisation of "wasi:cli" and improved error handling. The GitHub tag for the release is v0.3.0 (https://github.com/WebAssembly/WASI/releases/tag/v0.3.0). Early adopters such as Cloudflare Workers and Fastly Compute have begun testing the new modules in preview environments.
These additions let WebAssembly code open TCP/UDP connections and interact with a sandboxed file hierarchy, moving the platform closer to native‑like capabilities. That could reduce the need for custom host bindings and make it easier to port existing server‑side tools to Wasm.
The upgrade is incremental, not a wholesale redesign – expect more APIs to land in future minor releases before the spec stabilises.