Clone this repo:
  1. 35bbfa5 [document] Specify binary format (#455) by rossberg-chromium · 15 hours ago master
  2. 671b08d Update PLDI paper to final version by rossberg-chromium · 6 days ago
  3. dc46f28 Add memory trapping tests for lower bound as well and test load as well as stores (#459) by Michael Ferris · 7 days ago
  4. c11a7ad Add tests for malformed global initializer expressions (#465) by rossberg-chromium · 7 days ago
  5. 968329b Fix test (#464) by Andrew Scheidecker · 7 days ago

Build Status


This repository holds a prototypical reference implementation for WebAssembly, which is currently serving as the official specification. Eventually, we expect to produce a specification either written in human-readable prose or in a formal specification language.

It also holds the WebAssembly testsuite, which tests numerous aspects of conformance to the spec.

View the work-in-progress spec at

At this time, the contents of this repository are under development and known to be “incomplet and inkorrect”.

Participation is welcome. Discussions about new features, significant semantic changes, or any specification change likely to generate substantial discussion should take place in the WebAssembly design repository first, so that this spec repository can remain focused. And please follow the guidelines for contributing.