WebTransport Working Group Charter

This charter has been replaced by a newer version.

The mission of the WebTransport Working Group is to develop APIs that enable data transfer between browsers and servers with support for multiple data flows, unidirectional data flows, out-of-order delivery, variable reliability and pluggable protocols.

Join the WebTransport Working Group.

Start date 08 September 2020
End date 30 September 2022
Chairs Will Law (Akamai), Jan-Ivar Bruaroey (Mozilla)
Team Contacts Yves Lafon (0.15 FTE)
Meeting Schedule Teleconferences: approximately 1 per month
Face-to-face: we will meet during the W3C's annual Technical Plenary week; additional face-to-face meetings may be scheduled by consent of the participants, usually no more than 3 per year.


The deployment of the QUIC protocol standardized in IETF (e.g. in the context of HTTP3) is expected to make QUIC support widely available, opening up the possibility to establish new types of network connections in Web applications for client-server data transfer (e.g. unreliable, unordered).

The WebTransport Working Group, in collaboration with the IETF WebTransport Working Group develops APIs that enable Web developers to make use of these new network capabilities, including possible fallback mechanisms to handle scenarios when a QUIC connection cannot be established.

These capabilities are expected to be useful in a wide variety of contexts where network performance has perceivable impacts on user experience, such as media streaming or cloud gaming.


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

Draft state indicates the state of the deliverable at the time of the charter approval. Expected completion indicates when the deliverable is projected to become a Recommendation, or otherwise reach a stable state.

Normative Specifications

The Working Group will deliver the following W3C normative specifications:

WebTransport API

This specification defines a set of ECMAScript APIs to allow data to be sent and received between a browser and server, implementing pluggable protocols underneath with common APIs on top.

Draft state: Adopted from Web Platform Incubator Community Group

Expected completion: Q1 2023

Other Deliverables

Other non-normative documents may be created such as:

  • Use case and requirement documents;
  • Test suite and implementation report for the specification;
  • Primer or Best Practice documents to support web developers when designing applications.


  • September 2020: First teleconference
  • January 2021: FPWD for WebTransport
  • Q2 2022: CR for WebTransport

Success Criteria

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

Each specification should contain a section detailing any known security and privacy implications, and suggested mitigation strategies for implementers, web authors, and end users. The group should not publish a specification if acceptable mitigation strategies cannot be found.

There should be testing plans for each specification, starting from the earliest drafts.

To promote interoperability, all changes made to specifications after implementations emerge should have tests.


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. The Working Group is encouraged to engage collaboratively with the horizontal review groups throughout development of each specification. The Working Group is advised to seek a review at least 3 months before first entering CR and is encouraged to proactively notify the horizontal review groups when major changes occur in a specification following a review.

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

W3C Groups

HTML Working Group
The HTML Working Group publishes the W3C Recommendation of the WebSockets API which may play a role in fallback scenarios when a WebTransport connection cannot be established.
Web Real-Time Communications Working Group
The WebRTC API developed by the WebRTC Working Group enables data transfer between peers with similar charactestics to the ones enabled by WebTransport, and may consider adopting the WebTransport API for peer-to-peer data transfer.
Media and Entertainment Interest Group
The Media and Entertainment Interest Group gather use cases and requirements around media on the Web, including media streaming. Media streaming is expected to be a possible field of application of the WebTransport API.
Media Working Group
The Media Working Group may develop an Encoders/Decoders API which, together with the WebTransport API, could be used to stream media content (e.g. in low-latency scenarios such as cloud gaming). Interoperability requirements between the APIs may need to be considered.
Web and Networks Interest Group
The Web & Networks Interest Group is looking at how evolutions of network technologies impact Web applications, of which the WebTransport API is a key recent element.
Web Application Security Working Group
The mission of the Web Application Security Working Group is to develop security and policy mechanisms to improve the security of Web Applications, and enable secure cross-origin communication.

External Organizations

IETF WebTransport Working Group
The IETF WebTransport Working Group defines the protocols and protocols extensions which the API will use to establish its client-server connections. The two groups expect to coordinate closely.
IETF Multiplexed Application Substrate over QUIC Encryption Working Group
The IETF Multiplexed Application Substrate over QUIC Encryption Working Group develops mechanism(s) that allow configuring and concurrently running multiple proxied stream- and datagram-based flows inside an HTTPS connection.
The WHATWG maintains the WebSockets API (currently as part of the HTML Living Standard) which may play a role in fallback scenarios when a WebTransport connection cannot be established. It also maintains the Streams Standard which is expected to inform how WebTransport exposes data transfer, and Fetch which might be impacted by the use of WebTransport.


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 working 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.

The group also welcomes non-Members to contribute technical submissions for consideration upon their agreement to the terms of the W3C Patent Policy.

Participants in the group are required (by the W3C Process) to follow the W3C Code of Ethics and Professional Conduct.


Technical discussions for this Working Group are conducted in public: the meeting minutes from teleconference 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 on a public repository and may permit direct public contribution requests. The 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 WebTransport Working Group home page.

Most WebTransport 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 its repositories' GitHub issues and its public mailing list public-webtransport@w3.org (archive). The public is invited to review, discuss and contribute to this work.

The group may use a Member-confidential mailing list for administrative purposes and, at the discretion of the Chairs and members of the group, for member-only discussions in special cases when a participant requests such a discussion.

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 and 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 (Version of 5 February 2004 updated 1 August 2017). 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.

Charter History

The following table lists details of all changes from the initial charter, per the W3C Process Document (section 5.2.3):

Charter Period Start Date End Date Changes
Initial Charter 08 September 2020 30 September 2022 Initial charter