Interop 2027 opens its call for proposals

The Interop 2027 project is now accepting feature proposals. The process begins with a call for proposals on the web-platform-tests Interop repository, and submissions will be accepted until September 23rd. After that date, all proposed features will be evaluated according to the project's published selection process.

Interop's goal is to take features that have already cleared the standards process and push them toward full cross-browser interoperability. That means the first thing to check before submitting a proposal is whether the feature has a stable specification with no outstanding objections from browser vendors. In past years, features selected for the project have typically been implemented in at least one browser already.

Besides a stable implementation, a successful proposal needs a solid test suite. A feature's progress in Interop is measured by how well browsers pass its associated tests, so enough tests must exist up front to make the project work meaningful. The Proposal Guide on the Interop repository outlines these requirements and lists additional signals that can strengthen a submission.

Signals for a strong candidate

Progress on the accepted Interop 2026 proposals has been strong across all browsers, with each engine in a better position than it was at this time last year. Many of the features included this year had appeared prominently in developer surveys like The State of CSS, or ranked in the top 20 of the developer signals repository. Those same sources offer hints for what might make a compelling Interop 2027 candidate.

Two public resources are worth consulting when preparing a proposal. The webstatus.dev dashboard can show which features currently meet the stability and implementation criteria. The developer signals repository meanwhile contains published use cases that can be cited as supporting evidence for a proposal.

Getting involved without a proposal

Even developers without a feature to submit can help shape the project. The list of proposals on the Interop repository is open for review, and commenting on or reacting to submissions helps indicate which features matter most to the community. Sharing the call for proposals within developer networks also helps ensure the project hears from as broad a range of voices as possible.