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Explainer https://github.com/WICG/nav-speculation/blob/main/prerendering-cross-origin-iframes.md Specification https://wicg.github.io/nav-speculation/prerendering.html Summary Prerenders cross-origin iframes with an opt-in response header. Browsers will now prerender all cross-origin frames if the top-level frame's HTTP response includes the Supports-Loading-Mode: prerender-cross-origin-frames. Blink component Blink Web Feature ID speculation-rules Motivation By default, navigational prerendering delays the loading of all cross-origin iframes until the referring page activates the prerendered page. However, there are some cases where cross-origin iframes are particularly important to an application, such that delaying them negates many of the benefits of prerendering. Initial public proposal https://groups.google.com/a/chromium.org/g/blink-dev/c/KP1f2UTqCgM/m/q_EQ5ceXHgAJ TAG review https://github.com/w3ctag/design-reviews/issues/1207 TAG review status Issues addressed Origin Trial Name Prerendering cross-origin iframes Goals for experimentation Gather feedback from web authors who already are interested in this feature. Chromium Trial Name Prerender2CrossOriginIframes Origin Trial documentation link https://github.com/WICG/nav-speculation/blob/main/prerendering-cross-origin-iframes.md WebFeature UseCounter name kPrerender2CrossOriginIframes Risks Interoperability and Compatibility The entire speculative loading feature is a progressive enhancement, so in general risks are low in this area. Gecko: No signal (https://github.com/mozilla/standards-positions/issues/1376) No signal as of 2026-10-15 WebKit: No signal (https://github.com/WebKit/standards-positions/issues/636) No signal as of 2026-10-15 Web developers: Positive Our partners have given positive feedback on this feature. Other signals: WebView application risks Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications? No. Debuggability The cross-origin iframe prerendering should be debuggable as well as top frame's one: https://developer.chrome.com/docs/devtools/application/debugging-speculation-rules#prerender Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)? No Is this feature fully tested by web-platform-tests? Yes Flag name on about://flags "prerender2-cross-origin-iframes" from M148 Finch feature name Prerender2CrossOriginIframes Rollout plan Will ship enabled for all users Requires code in //chrome? False Tracking bug https://issues.chromium.org/issues/440387014 Availability expectation Feature is available only in Chromium browsers for the foreseeable future. Adoption expectation Feature is used by specific partner(s) to provide functionality within 12 months of launch in Chrome. Adoption plan One of our partners has already joined in origin trial in Chrome and shows better performance result. Non-OSS dependencies Does the feature depend on any code or APIs outside the Chromium open source repository and its open-source dependencies to function? No. Estimated milestones Shipping on desktop 158 Origin trial desktop first 147 Origin trial desktop last 152 Origin trial extension 1 end milestone 158 Shipping on Android 158 Shipping on WebView 158 Shipping on iOS 158 Anticipated spec changes Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (eg links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (eg, changing to naming or structure of the API in a non-backward-compatible way). No information provided Link to entry on the Chrome Platform Status https://chromestatus.com/feature/5112398709129216?gate=5121426126405632 Links to previous Intent discussions Intent to Prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/68b670ba.050a0220.270bc4.0593.GAE%40google.com Intent to Experiment: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAAEV3p%3DzhNhfOpe8x%3DRKgxYFS9GCq_q-c8knZYRBRuijQ27o8w%40mail.gmail.com Intent to Extend Experiment 1: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6a45fcf5.198129d7.1d0cd0.0014.GAE%40google.com This intent message was generated by Chrome Platform Status. -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6ad07271.44af066b.11268.0096.GAE%40google.com.
