To get started using WASI, see the intro document and the tutorial.
For more detail on what WASI is, see the overview.
For specifics on the API, see the API documentation. Additionally, a C header file describing the WASI API is here.
The WASI libc repository is wasi-libc.
For some discussion of capability-based design, see the Capabilities document.
For some discussion of WASI's design inspiration, see the Background document.
For background on some of the design decisions in WASI, see the rationale.
For some ideas of things that we may want to change about WASI in the short term, see the possible changes document. For longer-term ideas, see the possible future features document.