Chrome 155 Scheduled for October 6, 2026: JPEG XL Images, Post-Quantum WebCrypto and What to Test
Chrome 155 is scheduled to reach the stable channel on October 6, 2026. Its release notes list no removals, so existing websites should keep working, but the release adds JPEG XL image decoding, post-quantum algorithms in the Web Cryptography API, a way for pages to pause sound from hidden embedded frames, and new window controls for installed web apps. For most businesses the practical question is which of these are worth using and what to retest.
Google publishes the details in the Chrome 155 release notes on Chrome Status, which we read on October 6, 2026. If your site or web app is due a round of browser testing or an image performance review, that falls under the website and web application development services a development partner would normally handle.
What is new in Chrome 155?
Chrome 155 adds new capabilities for images, cryptography, embedded media, styling and installed web apps, and the release notes we read list no removals or deprecations. The headline items are:
- JPEG XL decoding. Chrome can display images in the JPEG XL format (image/jxl), using a decoder written in the Rust programming language.
- New Web Cryptography algorithms. The notes list ML-KEM, ML-DSA, ChaCha20-Poly1305 and X-Wing, described as post-quantum cryptography plus a common symmetric cipher.
- Pausing media in hidden iframes. A new permission policy lets a page pause audible media in embedded frames that are currently hidden.
- Additional windowing controls. Web apps holding the window-management permission can maximize, minimize and restore their windows and prevent resizing.
- CSS and JavaScript additions. These include the margin-trim property, the symbols() function, text-decoration-skip-spaces, and importing text files as JavaScript modules.
The notes also list WebTransport improvements and issuance support in the Digital Credentials API, which lets a website start adding a digital credential to a user's mobile wallet app.
Will Chrome 155 break my existing website?
It is unlikely, because the Chrome 155 release notes describe additions rather than removals. Browser releases break sites mainly when an old feature is switched off or a default behavior changes, and neither appears in the notes for this version.
Two cautions apply. First, a release with no listed removals can still contain bug fixes that change how an edge case renders, so a quick check of your key pages after the update is still sensible. Second, security fixes are published separately on the Chrome Releases blog, which is where Google posts each stable channel update. As of October 6, 2026, the most recent desktop stable post we saw there was dated October 1, 2026, so the Chrome 155 announcement had not yet appeared when we checked.
What does JPEG XL support in Chrome mean for my site's images?
It means Chrome users can now be served JPEG XL files, which adds one more modern image format to choose from. The release notes say the format support enables progressive loading, high dynamic range and animation.
Should we convert our images to JPEG XL now?
Not as a wholesale switch. Visitors will be on older Chrome versions and other browsers for some time, so any JPEG XL image needs a fallback in a format every visitor can display. Your developer can serve JPEG XL to browsers that say they accept it and an existing format to the rest, and most image content delivery services can do this negotiation automatically once they support the format. We did not verify the support status of individual image services or other browsers for this article, so ask your provider.
Who benefits most?
Sites where images carry the business: e-commerce catalogs, property listings, photography, travel and media. If your pages are light on images, this change will make little practical difference.
What is post-quantum cryptography in Chrome 155, and do I need to act?
Chrome 155 adds post-quantum algorithms to the Web Cryptography API, and most businesses do not need to act on it today. The Web Cryptography API is a set of browser functions that let a web application encrypt, decrypt and sign data inside the page. The release notes describe the addition as giving developers browser-provided implementations of quantum-resistant algorithms, meaning algorithms designed to stay secure against future quantum computers.
This matters to a narrow group: applications that do their own encryption in the browser, such as end-to-end encrypted messaging, password managers, document signing and some healthcare or financial tools. For those teams, native support removes the need to ship a separate cryptography library to every visitor. It does not change how your site's HTTPS connection works, and it is not a reason to rewrite existing encryption without a security review. Our web application security checklist covers the basics that matter more for most sites.
Who is affected by the hidden iframe media change?
Sites that embed third-party content, and companies whose content is embedded on other sites. The new permission policy, named media-playback-while-not-visible, allows the embedding page to pause audible media in an embedded frame while that frame is hidden.
The release notes describe this as something the embedding page chooses to apply, not a new default. If you run a site with embedded video players, chat widgets or advertisements, it gives your developer a tool to stop sound playing from a part of the page the visitor cannot see. If you supply an embeddable player or widget, your content may now be paused by host pages that adopt the policy, so test that it resumes cleanly.
What should a business do now?
Treat Chrome 155 as a routine release that deserves a short check rather than a project. A reasonable checklist:
- After Chrome updates on your own machine, open your most important pages and complete one real transaction: checkout, sign-in, a form submission or a booking.
- Ask your developer whether any open issue in your backlog relates to embedded media, installed web app windows or image weight, since this release adds tools for each.
- If images dominate your pages, ask your image or hosting provider about its JPEG XL plans before doing any conversion work yourself.
- If your application encrypts data in the browser, add post-quantum algorithms to the agenda of your next security review.
- Check the Chrome Releases blog for the stable channel post and its list of security fixes, and make sure company devices are set to update.
Google notes on its Chrome for Developers release notes page that release notes from Chrome 155 onward are available on Chrome Status, so that is the place to look for future versions too.
Quick answers
When is Chrome 155 released?
Chrome Status lists the scheduled stable release of Chrome 155 as October 6, 2026. Chrome updates reach individual devices over time, so not every user receives a new version on the first day.
Does Chrome 155 remove any web features?
The Chrome 155 release notes on Chrome Status, as read on October 6, 2026, list new features and no removals or deprecations. Existing websites should not need changes because of this release.
Does Chrome support JPEG XL images?
Yes, according to the Chrome 155 release notes, which add decoding of JPEG XL (image/jxl) images. Sites should still provide a fallback format for visitors on older Chrome versions or other browsers.
What post-quantum algorithms does Chrome 155 add to WebCrypto?
The Chrome 155 release notes list ML-KEM and ML-DSA as post-quantum additions to the Web Cryptography API, along with X-Wing and the ChaCha20-Poly1305 cipher. They matter mainly to web apps that encrypt or sign data inside the browser.
What is the media-playback-while-not-visible permission policy?
It is a permission policy added in Chrome 155 that lets a web page pause audible media playing in an embedded iframe while that iframe is hidden. The embedding page chooses whether to apply it.
Conclusion
Chrome 155, scheduled for stable release on October 6, 2026, is an additive release: JPEG XL images, post-quantum options for in-browser cryptography, control over sound from hidden embeds and better window handling for installed web apps. Nothing in the release notes requires urgent changes to an existing site. The useful response is a short test of your key journeys and a conversation about whether any of the new capabilities solves a problem you already have.
Entrant Technologies builds websites, web applications, mobile apps and custom software. If you would like a second opinion on how a browser release affects your site, contact us and we will take a look.