Google Images and Discover do not support JPEG XL yet

By Tom Whitfield

What does Google’s documentation list?

Google’s image SEO documentation lists seven Search-supported image formats—BMP, GIF, JPEG, PNG, WebP, SVG and AVIF—and omits JPEG XL, Google Search Advocate John Mueller said on Bluesky on Oct. 15.

Mueller’s thread linked the documentation and stated:

“FWIW if you’re hoping to get images shown in Google Images & as previews in Discover, etc – JPEG-XL is currently not supported”

Google’s documentation says Search can find an image in the src attribute of an img element even when a picture or other tag contains it. The page recommends a fallback URL in src because some browsers and crawlers do not support, or cannot read, picture or srcset.

Google’s indexable file-type list repeats the same seven formats and does not mention JPEG XL. Google said the image SEO page was last updated on March 2. As of Oct. 20, the Search Central documentation changelog had no JPEG XL entries.

Takeaway: Google expects an img source in a listed format, even when picture also offers JPEG XL.

Where do browsers stand?

SE Journal reported that JPEG XL support arrived in Chrome 155. Google began releasing it to a small percentage of users on Sept. 23 and widened the rollout on Oct. 6. Firefox 158 added the format on Oct. 13.

SE Journal also dates Safari support to version 17 in 2023. The webstatus.dev browser tracker classified JPEG XL as having limited availability and noted no Edge release.

Chrome’s team says JPEG XL provides 30-50% better compression than JPEG, along with lossless compression and HDR. The team recommends testing both AVIF and JPEG XL.

Chrome’s team believes JPEG XL will have greater value for users requiring lossless compression or higher-fidelity images, particularly for photographs.

Takeaway: Chrome, Firefox and Safari support JPEG XL; webstatus.dev still labels availability limited and records no Edge release.

How can publishers serve JPEG XL safely?

In the same exchange, Chrome developer advocate Barry Pollard said developers should include fallback options because JPEG XL is new to Chrome and Firefox. He asked whether Search could handle those fallbacks within a picture element.

Mueller answered:

“The picture element includes an img element, so that would work for any search engine (or other page parsing setup). I have not heard of any problems with people doing this kind of progressive enhancement”

Google’s documentation and Mueller’s reply support four publishing checks:

• Serve JPEG XL as the picture source, with JPEG, WebP or AVIF in the img src attribute.
• Keep a fallback URL in the img src; Google’s page includes this advice for browsers and crawlers that cannot read picture or srcset.
• Point og:image and schema.org image markup to one of Google’s seven listed formats.
• Add a larger preview through schema.org markup or the og:image meta-tag; Google says the image’s size can influence the thumbnail shown in Discover.

SE Journal’s practical example says a .jxl image can appear in Chrome and Firefox, while Google Images and Discover do not currently support .jxl.

Takeaway: Publishers can test JPEG XL in picture without replacing the supported image Google expects in img.

What does the AVIF precedent show?

Google released Chrome 85 with AVIF support in August 2020. On Aug. 30, 2024, Google announced AVIF support in Search on its Search Central blog, approximately four years later.

Google’s Aug. 30 announcement indicated that AVIF worked across every major browser. The webstatus.dev tracker said Edge was the last major browser to add it, doing so in January 2024.

Neither Mueller’s post nor Google’s image SEO page provides a JPEG XL timetable. Neither did the Search Central documentation changelog contain a JPEG XL entry as of Oct. 20.

Takeaway: Publishers should watch Google’s image SEO format list and Search Central blog for a JPEG XL addition; without one, Google has supplied no launch date, and publishers need one of the seven listed fallbacks.