Apple Calls for Developer Ideas for Interop 2027

Apple’s WebKit crew has rolled out the invitation for the next round of Interop – a collaborative, cross‑browser push that aims to smooth out the quirks we all hit when building for the modern web. The open call kicked off on September 3 and will stay open until September 23, giving developers a modest window to pitch what they think should be the focus for Interop 2027.

To give you some background, Interop grew out of the 2022 Compat project, where Apple teamed up with Google, Microsoft, Mozilla, Bocoup and Igalia. They identified about fifteen problem spots where browsers just weren’t speaking the same language. The experiment worked so well that it turned into an annual effort. Every year a fresh set of focus areas is chosen, largely based on community proposals, and the progress is measured with a shared suite of Web Platform Tests (WPT).

Last year’s results were pretty encouraging. Interop 2025 started with a paltry 29 % of the targeted tests passing across all major browsers, and by year‑end that figure had vaulted to 97 %. For 2026 the WebKit team announced twenty focus areas – everything from the Navigation API and View Transitions to WebRTC and WebTransport – many of which came straight from developers who answered the previous open call.

This time around, Apple is looking for ideas that sit on solid, mature web standards and can be wrapped in an automated test. If a technology is still in its infancy or lacks sufficient test coverage, the team suggests submitting it as an “Interop Investigation” instead of a full‑blown focus area.

So, what makes a proposal stand out? Apple breaks it down into five simple buckets:

• Specific: Pinpoint one concrete interoperability snag – think font-size-adjust, not “general typography”.
• Impactful: Show why the issue matters, preferably with a real‑world use case from your own work.
• Valuable: Explain the benefit for developers or end‑users and, if possible, back it up with data (surveys, bug reports, etc.).
• Stable: Link to the stable specification that defines the feature – the MDN docs are a good place to start.
• Tested: Cite existing WPT coverage or outline how new tests could be added this fall.

The Interop Proposers Guide, linked in the official announcement, walks you through the submission process step by step. Submissions are made via GitHub issues – either by opening a brand‑new issue or by bolstering an existing one with additional details. Apple explicitly encourages developers to add weight to already‑filed proposals rather than flooding the repo with duplicate ideas.

Keep in mind that reviewers may not be intimately familiar with every proposal from the previous year, so take the time to make your case crystal clear. Explain why the problem hurts developers today, how widely the technology is used, and why fixing it should trump other candidates on the list.

All told, this is a rare chance for anyone who builds web‑centric products to have a say in the standards that shape browsers for the next few years. If you’ve run into a sticky cross‑browser bug that still feels unresolved, now might be the moment to turn that frustration into a concrete, testable proposal.