New in Chrome 139

Rachel Andrew

Published: August 5, 2025

Chrome 139 is rolling out now, and this post shares some of the key features from the release. Read the full Chrome 139 release notes.

Highlights from this release:

On-device Web Speech API

Adds on-device speech recognition support to the Web Speech API.

Websites can query the availability of on-device speech recognition for specific languages, prompt users to install the necessary resources for on-device speech recognition, and choose between on-device or cloud-based speech recognition as needed. This addition means that websites can ensure that audio and transcribed speech are not sent to a third-party service for processing.

CSS corner shaping

You can now style corners in CSS, on top of the existing border-radius by specifying the shape or curvature of the corner. This lets you create shapes like squircles, notches, and scoops, and animate between them. Learn more in this post from Amit Sheen.

CSS custom functions

Custom functions are similar to custom properties, but instead of returning a single, fixed value, they return values based on other custom properties, parameters, and conditionals.

CSS functions are defined using the @function rule, and are part of the CSS Custom Functions and Mixins specification.

@function --negate(--value) {
result: calc(var(--value) * -1);
}

div {
--gap: 1em;
margin-top: --negate(var(--gap));
}

And more

Of course there's plenty more:

  • You can now let sites that control multiple subdomains and top level domains be presented as a single web app with the "scope_extensions" web app manifest field.
  • Chrome now recognizes all valid JSON MIME types as defined by the WHATWG mimesniff specification.
  • The request-close invoker command brings the functionality of the requestClose() JavaScript event to the declarative invoker commands API.

Further reading

This covers only some key highlights. Check the following links for additional changes in Chrome 139.

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As soon as Chrome 140 is released, we'll be right here to tell you what's new in Chrome!