WebAssembly Working Group Charter

The March 2020 version of this charter is newer.

The mission of the WebAssembly Working Group is to standardize a size- and load-time-efficient format and execution environment, allowing compilation to the web with consistent behavior across a variety of implementations.

Join the WebAssembly Working Group.

Start date 3 August 2017
End date 28 February 2020
Chair Ben Smith (Google)
Previous chair Brad Nelson (Google)
Team Contacts Eric Prud'hommeaux (0.15 FTE)
Meetings Meetings will be scheduled in accordance with the W3C Process Document.
Teleconferences: We will meet by teleconference approximately once per month.
Face-to-face: We will meet during the W3C’s annual W3C Technical Plenary / Advisory Committee Meetings Week; additional face-to-face meetings may be scheduled, usually no more than 3 per year, per Process. Teleconference access to face-to-face meetings will be made available.


The scope of the WebAssembly Working Group comprises addressing the need for native-performance code on the Web in applications ranging from 3D games to speech recognition to codecs—and in any other contexts in which a common mechanism for enabling high-performance code is relevant—by providing a standardized portable, size-, and load-time-efficient format and execution environment that attempts to maximize performance and interoperate gracefully with JavaScript and the Web, while ensuring security and consistent behavior across a variety of implementations.

Since the inception of the Web, various technologies have been developed to allow “native” applications on the Web. Techniques such as user consent with digital signatures and Virtual Machines with different capabilities than JavaScript failed to be robust in the face of increasingly high security requirements. Later efforts like Native Client, which featured robust security, failed to achieve cross-browser adoption. Cross-compilation to JavaScript using Emscripten, especially using the machine-optimization subset called asm.js, achieved some degree of success. However, consistent cross-browser performance, shared memory threads, and other machine features have proved elusive.

The WebAssembly format and execution environment address the shortcomings of those previous efforts.

Success Criteria

In order to advance to Proposed Recommendation, the WebAssembly specification is expected to have at least two independent implementations of each feature it defines.

The WebAssembly specification should contain a section detailing any known security or privacy implications for implementors, Web authors, and end users.

The WebAssembly specification should contain a section describing known impacts on accessibility to users with disabilities, ways the specification features address them, and recommendations for minimizing accessibility problems in implementation.


More detailed milestones and updated publication schedules are available on the group publication status page.

Normative Specifications

The WebAssembly Working Group will deliver the following normative specification:


This specification defines a size- and load-time-efficient format and execution environment allowing compilation to the web with consistent behavior across a variety of implementations.

Draft state: In progress in WebAssembly CG

Expected completion v.1: Q2 2018

Expected completion v.2: Q4 2018

Expected completion v.3: Q2 2019

Revisions to the WebAssembly Recommendation will be produced twice each year (see the timeline), snapshotting changes that have been incrementally adopted by the Working Group. They will include a testsuite and implementation report for the specification. Each successive version will incrementally incorporate improvements to support more machine-level operations, increase performance, or to better interoperate with the web platform, including features such as:

  • Multiple return values
  • Multiple memories + tables
  • Threads + shared memory
  • SIMD
  • DOM/HTML integration
  • Garbage-collected object support
  • WebIDL interpretation for direct binding
  • Direct WebGL binding
  • Direct memory-mapped write access to IndexedDB objects

Other Deliverables

Other non-normative documents may be created, including:

  • An OCaml reference interpreter
  • Use cases and requirement documents
  • “Explainers”, primers, and best-practice documents


  • Q4 2017: First Public Working Draft of WebAssembly v.1
  • Q2 2018: Recommendation of WebAssembly v.1
  • Q2 2018: First Public Working Draft of WebAssembly v.2
  • Q4 2018: Recommendation of WebAssembly v.2
  • Q4 2018: First Public Working Draft of WebAssembly v.3
  • Q2 2019: Recommendation of WebAssembly v.3


For all specifications, this Working Group will seek horizontal review for accessibility, internationalization, performance, privacy, and security with the relevant Working and Interest Groups, and with the TAG. Invitation for review must be issued during each major standards-track document transition, including FPWD and CR, and should be issued when major changes occur in a specification.

Additional technical coordination with the following Groups will be made, per the W3C Process Document:

W3C Groups

WebAssembly Community Group
Coordination on seed specification to begin the standards process.
Web Platform Working Group
Coordination on WebAssembly-specific bindings to existing Web APIs (or interpreting existing WebIDL as it relates to WebAssembly).

External Organizations

TC39 - ECMAScript Standards Body
Coordination on integration with JavaScript, particularly on SharedArrayBuffer and its memory model
Khronos Group
Coordination on WebAssembly-specific bindings to WebGL.
WebGPU Community Group
Coordinate on WebAssembly interoperability, performance, and ergonomics.


To be successful, this Working Group is expected to have 6 or more active participants for its duration, including representatives from the key implementors of this specification, and active Editors and Test Leads for each specification. The Chairs, specification Editors, and Test Leads are expected to contribute half of a day per week towards the Working Group. There is no minimum requirement for other Participants.

The group encourages questions, comments and issues on its public mailing lists and document repositories, as described in Communication.

W3C Members are invited to join this Working Group. Individuals who wish to participate as Invited Experts (i.e., they do not represent a W3C Member) should refer to the policy for approval of Invited Experts. The group also welcomes non-Members to contribute technical submissions for consideration upon their agreement to the terms of the W3C Patent Policy.


Technical discussions for this Working Group are conducted in public: the meeting minutes from teleconferences and face-to-face meetings will be archived for public review, and technical discussions and issue tracking will be conducted in a manner that can be both read and written to by the general public. Working Drafts and Editor's Drafts of specifications will be developed in a public repository, and may permit direct public contribution requests. The group’s meetings themselves are not open to public participation, however.

Information about the group (including details about deliverables, issues, actions, status, participants, and meetings) will be available from the WebAssembly Working Group home page.

Most WebAssembly Working Group teleconferences will focus on discussion of particular specifications, and will be conducted on an as-needed basis.

This group primarily conducts its technical work on the public mailing list public-webassembly@w3.org (archive) and on GitHub issues. The public is invited to review, discuss and contribute to this work.

Decision Policy

This group will seek to make decisions through consensus and due process, per the W3C Process Document (section 3.3). Typically, an editor or other participant makes an initial proposal, which is then refined in discussion with members of the group and other reviewers, and consensus emerges with little formal voting being required.

However, if a decision is necessary for timely progress, but consensus is not achieved after careful consideration of the range of views presented, the Chairs may call for a group vote, and record a decision along with any objections.

To afford asynchronous decisions and organizational deliberation, any resolution (including publication decisions) taken in a face-to-face meeting or teleconference will be considered provisional. A call for consensus (CfC) will be issued for all resolutions (for example, via email and/or web-based survey), with a response period from one week to 10 working days, depending on the chair's evaluation of the group consensus on the issue. If no objections are raised on the mailing list by the end of the response period, the resolution will be considered to have consensus as a resolution of the Working Group.

All decisions made by the group should be considered resolved unless and until new information becomes available, or unless reopened at the discretion of the Chairs or the Director.

This charter is written in accordance with the W3C Process Document (Section 3.4, Votes), and includes no voting procedures beyond what the Process Document requires.

Patent Policy

This Working Group operates under the W3C Patent Policy (5 February 2004 Version). To promote the widest adoption of Web standards, W3C seeks to issue Recommendations that can be implemented, according to this policy, on a Royalty-Free basis. For more information about disclosure obligations for this group, please see the W3C Patent Policy Implementation.


This Working Group will use the W3C Software and Document license for all its deliverables.

About this Charter

This charter has been created according to section 5.2 of the Process Document. In the event of a conflict between this document or the provisions of any charter and the W3C Process, the W3C Process shall take precedence.