Interop 2026 proposal selection process

Interop 2026 is an effort to increase interoperability across browsers in key technical areas that are of high priority to web developers and end users. This effort is part of the web-platform-tests (WPT) project — an automated test suite for web standards — and run by a team of representatives from companies that make substantial contributions to browser rendering engines (including Apple, Bocoup, Google, Igalia, Microsoft, and Mozilla).

Please see the Interop 2026 Dashboard and Interop 2026 README for the current iteration of the project.

Each iteration of the project starts with an open call for proposals, followed by a selection and prioritization process by each participating organization. Final decision on the inclusion of a proposal is made by consensus. For Interop 2026, the timeline and the selection process is as described below.

Timeline

This is the general timeline for the Interop 2026 proposal selection process. The dates are centered on the Interop team meeting (Thursdays). Please note that the timelines are subject to change.

• Proposal submission window (~3 weeks): September 4th, 2025 to September 24th, 2025
• Proposal selection: Before December 11th 2025
• Scope of the Interop 2026 project published: February 5th, 2026.

Proposal selection process

The aim of the proposal selection process is to generate a shared understanding of the merits of each proposal, and converge on a decision about the most impactful areas in which we can improve interop on the web over 2026.

As in Interop 2024 and 2025, details of proposal selection and ranking remain participant confidential throughout the process. Final decisions will be published as the Interop team.

Confidentiality does not prevent participating organizations from sharing their own priorities or roadmaps, as distinct from positions in the proposal selection process.

Prior to Proposal Submission

Timeline: Before September 4th 2025

The interop team will develop a non-exhaustive set of signals/criteria that are considered important when assessing proposals. These will be made available to proposal authors, and used later in the process when championing and assessing different proposals. However they are not binding on any specific participant i.e. participants are free to consider additional criteria (such as individual resource constraints) and weigh the shared criteria as they choose.

Proposal Submission

Timeline: September 4th to September 24th

Members of the web community, including participants, will be invited to submit proposals for Interop 2026. These will take the form of issues on the Interop GitHub repository. Issue templates and documentation will be provided to guide proposers towards proposals that meet the formal criteria (e.g. around testability) and which can be assessed according to the agreed criteria.

Items from Interop 2025 which have not yet reached full interoperability will be automatically resubmitted, and will go through the process as for any other proposal. In addition new proposals can be submitted that extend the scope of existing focus areas (whether or not they have reached full interoperability).

As in previous years proposals can either be for focus areas or investigations. For simplicity the remainder of this document will only refer to focus area proposals, but this also covers proposals for investigation efforts.

Proposal Refinement

Timeline: September 24th to October 2nd

This phase would be used by the Interop team to ask proposal authors for any clarifications to help with evaluating the proposal.

Champion Selection

Timeline: October 2nd, 9th, 16th

Interop participants propose focus areas, consisting of one or more proposals, that they would like to champion. Proposals will initially be shared in time for the meeting on October 9th, and champions finalised on October 16th.

Where more than one participant wants to champion the same focus area proposal a single champion must be nominated for the remainder of the process.

There is no assigned limit to the number of proposals one participant may champion.

In case different focus areas are put forward with overlapping sets of proposals, the participants are encouraged to work out a way to divide the proposals into focus areas in a way that satisfies everyone. If this is impossible then carrying forward multiple competing focus area proposals is permitted, but final selections will only allow each proposal to appear in a single focus area.

Any proposal without a champion will not be carried forward.

Champion Evidence Gathering

Timeline: October 23rd, 30th

Champions gather evidence of the impact of their proposals, using the rubric developed earlier. Specific participants may also be asked to provide (publicly available) information for all proposals where that participant has ownership of the information (e.g. standards positions, use counter data).

Focus Area Proposal Presentation

Timeline: November 6th (double-length meeting)

Each participant gets 15 minutes of meeting time to present the proposals they are championing, and make the case that they should be considered a priority for inclusion in Interop 2026.

Proposal Ranking

Timeline: Before December 4th

Participants rank each proposal as P1 (highest priority) to P3 (lowest priority), or veto.

There is no preset limit on how many proposals each participant may assign each rank.

Initial rankings are submitted in time for the December 4th meeting.

Focus Area Selection

Timeline: December 4th, 11th and 18th

Focus areas with any vetoes are eliminated.

Proposals that have strong positive consensus (e.g. majority P1 rankings, no P3 rankings) are adopted. Proposals with a strong consensus of low priority (e.g. many P3 ranking and no P1 ranking, or many P3 and P1 only from the champion) are dropped.

Proposals with mixed rankings are ordered according to the number of P1 rankings, followed by the number of P2 rankings, followed by the number of P3 rankings. Starting from the top of the ordered list participants who ranked the proposal lower are given an opportunity to explain their concerns, and suggest any adjustments that would change their perspective. Proposal champions get final say on whether to adjust their proposals in response to this feedback.

Following each meeting participants may adjust their rankings for the remaining proposals up or down in response to discussions, any agreed changes to the proposals, or the overall composition of the project, and the process repeats in the following meeting.

Before the end of the December 18th meeting there's a final decision on any proposals without a clear resolution, and formal call for consensus on the set of selected focus areas.

Communication and Publication

Timeline: December 18th - February 5th 2026

Launch date is finalized. Focus area tests are labeled. Feedback for proposal authors written.

Launch

Timeline: February 12th 2026

The Interop 2026 dashboard is published. Proposal authors are provided with feedback and the original GitHub issues are closed. Participants publish announcements of the launch.