WebAssembly System Interface

The WebAssembly System Interface (WASI) is a set of APIs for WASI being developed for eventual standardization by the WASI Subgroup, which is a subgroup of the WebAssembly Community Group.

WASI started with launching what is now called Preview 1, an API using the witx IDL, and it is now widely used. Its major influences are POSIX and CloudABI.

WASI 0.2 (Preview 2) is a modular collection of APIs defined with the Wit IDL, incorporating many of the lessons learned from WASI 0.1, including support for a wider range of source languages, modularity, a more expressive type system, and virtualizability.

WASI 0.3 (Preview 3) is the current preview. It builds on WASI 0.2, replacing the earlier explicit streams and polling interfaces with the component model's native, composable async functionality via the future and stream types.

Find the APIs

Development of each API happens in its own repo, which you can access from the proposals list.

This repo is for general discussion, as well as documenting how we work and high-level goals.

Propose a new API

If you would like to create a new proposal, get started with our Contributing guide.

All new API proposals should use the new format and the new repo structure that is shown in the proposal template.

See the Wit in WASI document for more information about using Wit for WASI proposals.