Written By published September 3, 2026

The Interop 2027 call for proposals is open, submit your ideas now!

Over the past six years, the Interop project has helped bring key web platform features to a state where developers can rely on them across browsers. Technologies such as CSS layout and utilities, View Transitions, anchor positioning, popover, and shadow DOM have all benefited from the focused effort that Interop makes possible.

This year, browser vendors have continued to work across a broad set of focus areas including View Transitions, Navigation API, CSS Anchor Positioning, WebRTC, WebTransport, Dialogs and Popovers, custom highlights, container style queries, and more. These efforts are helping move the web platform toward a future where developers can spend less time working around browser differences and more time building great experiences.

Interoperability remains one of the most important challenges facing the web. New capabilities are constantly being standardized and implemented, but they’re most valuable when they work consistently everywhere. That’s why the Interop project continues to evolve each year, guided by input from developers, framework authors, browser vendors, and standards communities.

Today, we’re opening the proposal process for Interop 2027.

If you’ve encountered a web platform feature that behaves differently across browsers, a standards-based capability that’s difficult to rely on today, or an area where better interoperability would unlock new opportunities, we want to hear from you.

The proposal submission period is open now and will remain open through September 23, 2026. The Interop team will review submissions and evaluate them using the Interop selection process, with the goal of publishing the final Interop 2027 scope early February 2027.

What makes a strong proposal?

The strongest Interop proposals share a few common traits:

• They solve a real developer problem. Make sure you explain how inconsistent browser behavior or missing support affect developers in practice.
• They have ecosystem impact. Evidence from developers, frameworks, libraries, issue trackers, surveys, or real-world sites helps demonstrate that a problem is worth solving.
• They’re about standards-based features. Features with a stable specification and broad standards support are better candidates for Interop.
• They can be measured. Interop relies on Web Platform Tests (WPT) to track progress, so proposals should either have strong existing test coverage or a clear path to adding it.
• They are scoped for meaningful progress. A focused, concrete proposal is often easier to evaluate and more likely to succeed than a broad request such as “improve CSS” or “fix forms everywhere.”

For more information, check the Interop Proposers Guide.

Submit your proposals now

Submit your ideas now, even if you’re unsure they qualify.

Even proposals that aren’t selected can help us understand where you’re experiencing pain and where future interoperability work is needed. On the Microsoft Edge team, we’re always listening to developer signals, and unselected Interop proposals often constitute clear needs from developers.

We track these needs, and others, on our Top Developer Needs dashboard to influence progress on the highest-impact, long-running issues. We’ll be refreshing this dashboard early next year.