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Microsoft Edge 142 web platform release notes (Oct. 2025)

The following are the new web platform features and updates in Microsoft Edge 142, which releases on October 30, 2025.

To stay up-to-date and get the latest web platform features, download a preview channel of Microsoft Edge (Beta, Dev, or Canary); go to Become a Microsoft Edge Insider.

Detailed contents:

Edge DevTools

See What's New in Microsoft Edge DevTools.

WebView2

See Release Notes for the WebView2 SDK.

CSS features

Below are the new Cascading Style Sheets (CSS) features in Microsoft Edge.

AccentColor and AccentColorText system colors

The AccentColor and AccentColorText system colors can now be used as CSS color values to access the system accent color that's specified on the user's device.

See also:

CSS font-language-override property

The font-language-override CSS property allows you to override the system language used for OpenType glyph substitution, by specifying a four-character language tag directly in CSS.

This enables finer-grained typographic control for multilingual content, or for fonts with language-specific glyph variants.

See also:

document.activeViewTransition property

The document.activeViewTransition property provides access to the currently running view transition, regardless of whether this transition is on a single webpage, or between two webpages.

The View Transition API allows you to create visual transitions between different states of a single webpage, or between multiple webpages.

  • For transitions within single webpages, the document.startViewTransition() method returns a transition object. The document.activeViewTransition property now provides access to this transition object, which means you no longer need to store the document.startViewTransition() return value.

  • For transitions between multiple webpages, the document.activeViewTransition property now gives you access to the currently running transition object, for the duration of the transition. This is in addition to the pageswap and pagereveal events.

See also:

Range syntax for style container queries and if() functions

The CSS @container style() queries and if() functions now support the range syntax. The range syntax makes it possible to compare custom properties and values by using the < and > operators.

For a comparison to be valid, both sides of the comparison must resolve to the same data type. The range syntax is limited to the following numeric types:

  • <length>
  • <number>
  • <percentage>
  • <angle>
  • <time>
  • <frequency>
  • <resolution>

Example comparing a custom property with a literal length:

@container style(--inner-padding > 1em) {
   .card { border: 2px solid; }
}

Example comparing two literal values:

@container style(1em < 20px) {
   ...
}

Example comparing a value from the attr() substitution function with a literal value:

.item-grid {
   background-color: if(style(attr(data-columns, type<number>) > 2): lightblue; else: white);
}

See also:

SVG features

Below are the new Scalable Vector Graphics (SVG) features in Microsoft Edge.

Support download attribute in SVG <a> element

The download attribute is now supported by SVG <a> elements.

The download attribute enables you to specify that the target of an SVG hyperlink should be downloaded rather than navigated to.

See also:

CSS width and height support for SVG <use> element

The SVG <use> element now supports the width and height CSS properties.

This allows you to control the sizing of SVG elements through CSS, such as to improve their responsiveness.

With this feature, the following two HTML snippets now produce the same output:

<svg width="100px" height="100px">
   <defs>
      <symbol id="sym" width="80" height="80">
         <rect width="100" height="100" fill="green" />
      </symbol>
   </defs>
   <use href="#sym" style="width:40px; height:40px" />
</svg>

<svg width="100px" height="100px">
   <defs>
      <symbol id="sym" width="80" height="80">
         <rect width="100" height="100" fill="green" />
      </symbol>
   </defs>
   <use href="#sym" width="40" height="40" />
</svg>

See also:

Web APIs

Below are the new Web API features in Microsoft Edge.

Clear the window.name value for cross-site navigations that switch browsing context group

Previously, the value of the window.name property was preserved throughout the lifetime of a browser tab, even when a cross-site navigation switched browsing context groups.

The window.name property is now cleared when a cross-site navigation switches browsing context groups.

See also:

clipboardchange event

The Clipboard API now fires a clipboardchange event whenever the content of the system clipboard changes.

The clipboardchange event provides an efficient alternative to polling techniques, such as using JavaScript to read the clipboard content at regular intervals of time.

See also:

dataTransfer property for insertFromPaste, insertFromDrop, and insertReplacementText input events

The input event objects of type insertFromPaste, insertFromDrop, and insertReplacementText now have a dataTransfer property, for better interoperability with other browsers.

The dataTransfer property provides access to the clipboard or drag-and-drop data when the user edits text within a contenteditable element. The same data is also available on the dataTransfer property of beforeinput events.

This feature only applies to contenteditable elements.

See also:

Show third-party iframe origins in the FedCM UI

Third-party iframe origins are now shown in the FedCM UI. Showing the third-party iframe's origin to the user is important, to help users make an informed decision about sharing their credentials with the third-party origin. The client_is_third_party_to_top_frame_origin Relying Party (RP) metadata property allows you to show the third-party origin in the FedCM iframe.

Previously, when using iframes with FedCM, the FedCM UI always displayed the origin from the top-level site, even if it differed from the iframe's origin. That works well when the iframe is conceptually part of the top-level site, even if its origin is different; for example, a top-level site at example.com might use a FedCM iframe at example-static.com, which it owns, but which is not meaningful to show to the user. In other cases, FedCM iframes might belong to third-party sites.

See also:

HSTS tracking prevention

HSTS tracking prevention mitigates user tracking by third-parties via the HTTP Strict Transport Security (HSTS) cache.

This feature only allows HSTS upgrades for top-level navigations, and blocks HSTS upgrades for sub-resource requests. Blocking such an HSTS upgrade prevents third-party sites from using the HSTS cache to track a user across the web.

See also:

Only fire pointerrawupdate events in secure contexts

Microsoft Edge now matches the specification and other browsers by only firing pointerrawupdate in secure contexts.

Previously, the pointerrawupdate event fired in both secure and insecure contexts, which didn't match the Pointer Events specification and other browsers.

See also:

Enable sticky user activation across same-origin navigations

The sticky user activation state is now preserved after a the user navigates to a webpage that's on the same origin.

This allows you to directly make use of web features that normally require user activation, such as those listed at Features gated by user activation, even after the user has navigated to another webpage of your website.

See also:

New PWA manifest update algorithm

The updating of installed PWAs uses a new algorithm. The new update algorithm makes the update process more deterministic and predictable, and gives you more control over whether, and when, updates should apply to existing installations of your app.

The new update algorithm has the following benefits:

  • Consistency: The algorithm provides a consistent way to detect when a manifest update should happen.

  • Reduced user interruptions: App users won't see the update dialog, except when it's strictly necessary, such as to confirm security-sensitive changes.

  • Browser flexibility: Microsoft Edge can now allow known, trusted apps to update without displaying a notification, and can block updates for known bad apps.

  • Developer control: You have more control over when the update dialog is shown to users.

  • Reduce network traffic: Unnecessary network traffic is minimized.

See also:

Web Speech API contextual biasing

You can now provide a list of phrases to the Web Speech API for contextual biasing in speech recognition. Listing recognition phrases provides the Web Speech API with an explicit mechanism to support contextual biasing.

Previously, the Web Speech API used generalized speech recognition models, and couldn't prioritize certain words or phrases, or adapt to user-specific or domain-specific vocabularies.

See also:

Origin trials in Microsoft Edge

The following are origin trials for new experimental APIs that are available in Microsoft Edge.

Origin trials let you try experimental APIs on your own live website for a limited time.

To learn more about origin trials, see Use origin trials in Microsoft Edge.

To see the full list of available origin trials, see Microsoft Edge Origin Trials.

AriaNotify API

Expires on October 14, 2025.

The AriaNotify API enables your app to directly tell a screen reader what to say when there's a non-user-initiated change in the content of a webpage. In the simplest scenario, you call ariaNotify("foo") on the document or on an element.

See Creating a more accessible web with Aria Notify.

Ad Selection API

Expires on November 30, 2025.

The Ad Selection API provides user-relevant ads on your site without using third-party cookies.

Acquisition Info API

Expires on December 18, 2025.

The Acquisition Info API supports third-party acquisition attribution for PWAs that were acquired through an app store or directly from the browser.

Chromium origin trials

Below are active Chromium origin trials which you can try in Microsoft Edge.

To see the full list of Chromium origin trials that are available in Microsoft Edge, see Microsoft Edge Origin Trials.

WebAssembly Custom Descriptors

Expires on June 16, 2026.

WebAssembly Custom Descriptors allows WebAssembly to store data associated with source-level types more efficiently in new custom descriptor objects.

WebGPU Compatibility Mode

Expires on April 21, 2026

WebGPU Compatibility Mode is an opt-in, lightly restricted subset of WebGPU capable of running older graphics APIs such as OpenGL and Direct3D11. The goal is to expand the reach of WebGPU applications to older devices that don't have the modern, explicit graphics APIs that core WebGPU requires.

Fetch retry

Expires on March 24, 2026.

Fetch retry allows web developers to indicate that a fetch() request should be retried, to have a greater guarantee on it being reliably sent, even if the network connection is erratic. This is especially important for keep-alive fetches, where the request might outlive the document, which can no longer watch for its failure and do a manual retry.

Prompt API

Expires on March 24, 2026

The Prompt API is an experimental web API that allows you to prompt a small language model (SLM) that is built into Microsoft Edge, from your website's or browser extension's JavaScript code. Use the Prompt API to generate and analyze text, or to create application logic based on user input, and discover innovative ways to integrate prompt engineering capabilities into your web application.

See also:

Incoming Call Notifications

Expires on May 19, 2026.

Extend the Notifications API to allow installed PWAs to send incoming call notifications -- that is, notifications that have call-styled buttons and a ringtone. This extension helps VoIP web apps create more engaging experiences by making it easier for users to easily recognize a calling notification and answer it. This feature also helps bridge the gap between native and web implementations of apps that have them both.

See also:

Full frame rate render blocking attribute

Expires on March 24, 2026

The new full-frame-rate render blocking attribute instructs the browser to render the page at a lower frame rate to reserve resources while parsing critical content. After the critical content has been parsed, the browser restores its normal frame rate.

For example <link rel="expect" href="#critical-content" blocking="full-frame-rate"> lowers the frame rate of the browser until the #critical-content element is parsed.

The full-frame-rate render blocking attribute is informational only. The browser may decide to lower the frame rate before parsing a blocking element, such as at the very beginning of the loading phase. The browser may also decide to restore the frame rate before the blocking element list becomes empty, such as after a timeout, or after certain user interactions.

Note

Portions of this page are modifications based on work created and shared by Chromium.org and used according to terms described in the Creative Commons Attribution 4.0 International License.