Hello, Tor Browser alpha has JPEG XL support behind the same pref as Firefox, but we won't enable it by default before Firefox for sure. At the time of writing, image.jxl.enabled is still true by default only in Firefox nightly builds. As far as I know, we haven't established a plan about what to do with it yet, and we are inheriting upstream's default. In other words, if nothing changes we'll enable it in Tor Browser when Mozilla does it in Firefox stable. Notice that Tor Browser 16.0 alpha is already on the ESR-153 branch and we are finalizing it to make it stable, therefore it is very unlikely JPEG XL will be enabled in our stable channel in the next 12 months (when 17.0 should be more or less ready to become the next-next stable). Please remember that enabling it in advance will make you stand out from a fingerprinting perspective. Best regards, Pier Angelo Vendrame On 8/27/26 10:38, mib via tor-dev wrote:

Hello everyone. Apologies if this is the wrong list to post to! If that's the case, please direct me elsewhere.

Firefox and Chrome recently announced their intent to (finally) support JPEG XL. Given the Tor browser bundle is based on Firefox, I'm curious when support would land? Any security considerations beyond Firefox's own, the whole reason for the half-decade delay? Will JXL be enabled by default or is support within TBB "mandatory" now that all major browsers have committed to support it before end of year?

I know for sure I'll be serving JPEG XL where possible and downgrading to JPEG transcodes when not, but given that wide-spread adoption isn't even close to guaranteed and any decent system would just transcode, is adoption urgent or should TBB wait to see it get properly battle-tested?

Not often a new image format lands in browsers. 🙂

Kind regards, — mib _______________________________________________ tor-dev mailing list -- tor-dev@lists.torproject.org To unsubscribe send an email to tor-dev-leave@lists.torproject.org