 Rachel Andrew Technical Writer [GitHub](https://github.com/rachelandrew) [LinkedIn](https://www.linkedin.com/in/rachelandrew) [Mastodon](https://front-end.social/@rachelandrew) [Bluesky](https://bsky.app/profile/rachelandrew.bsky.social) [Homepage](https://rachelandrew.co.uk)
Published: September 4, 2025
It's been seven months since [Interop 2025](https://wpt.fyi/interop-2025) kicked
off. Work on the focus areas for this year continues, but with an eye to the
future, today we're opening proposals for Interop 2026. From today through
September 24, 2025 the [feature submission form](https://github.com/web-platform-tests/interop/issues/new?template=focus-area-proposal.yml)
is open. Submit your ideas for features to become part of the Interop 2026
effort. As in previous years we expect to see a large number of feature
submissions, and all will be considered through [this
process](https://github.com/web-platform-tests/interop/blob/main/2026/selection-process.md).
## What makes a good proposal?
The Interop project aims to take things that have already been through the
standards process, and make them interoperable. Therefore, the first thing to
consider is whether your idea has a stable specification, and no outstanding
objections from one or more browser vendors. Past features have typically been
implemented in at least one browser before becoming part of the project.
Features that have a stable implementation should also have the other thing
that's needed for a successful proposal---a good test suite. The success of a
feature in the project is based on browsers passing these tests, so we need to
know that there are enough tests in the first place.
Find out more information by reading the [Proposal
Guide](https://github.com/web-platform-tests/interop/blob/main/proposal_guide.md).
This guide includes some additional signals that can help to boost the chances
of your proposal succeeding.
## Interop 2025 progress
For inspiration, take a look at the Interop 2025 focus areas. When we started
the project in February, the scores for each browser were as follows.
 Interop 2025 dashboard (as of February 13, 2025).
Our [post at the start of the project](https://web.dev/blog/interop-2025.md.txt) shared
some of the features we were most excited about. For example, same-document view
transitions which are now in Firefox Nightly as an Experimental feature.
That post also described additions to the
[``](https://developer.mozilla.org/docs/Web/HTML/Reference/Elements/details)
element---such as the
[`::details-content`](https://developer.mozilla.org/docs/Web/CSS/::details-content)
pseudo-element which shipped in Safari 18.4. In the same version Safari also
landed the sideways writing mode values, bringing that feature to Baseline Newly
available.
The ongoing [beta of Safari
26](https://developer.apple.com/documentation/safari-release-notes/safari-26-release-notes)
promises support for
[`overflow-block`](https://developer.mozilla.org/docs/Web/CSS/overflow-block)
and
[`overflow-inline`](https://developer.mozilla.org/docs/Web/CSS/overflow-block).
These logical properties were also included in Chrome 135 and will become
Baseline Newly available when Safari 26 ships to stable. This beta also includes
CSS anchor positioning, and many other features and fixes to improve the Safari
Interop score.
In addition, [mutation
events](https://developer.mozilla.org/docs/Web/API/MutationEvent) have now been
removed from all browsers.
You can see the improvements on the [Interop 2025
dashboard](https://wpt.fyi/interop-2025), and we still have a number of browser
releases to go before the end of the year.
 Interop 2025 dashboard (as of September 3, 2025).
We're excited to see more improvements to the web platform, and more features
becoming Baseline Newly available through Interop 2026---[get your proposals in
today](https://github.com/web-platform-tests/interop/issues/new?template=focus-area-proposal.yml)!