Clone this repo:
  1. 0a2e341 Add missing parameter to 'if' type (#511) by Stéphan Kochen · 29 hours ago master
  2. 800a85f Add test in traps.wast (#510) by Michael Ferris · 3 days ago
  3. 0798b0a Test js-api: add memory.grow test (#507) by Michael Ferris · 4 days ago
  4. 645c652 Test harness: fix assert_invalid, improve error messages (#505) by JF Bastien · 7 days ago
  5. 3725d1a Rectify licensing (#496) by rossberg-chromium · 10 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.