LGTM1 to deprecate. This feature removal sounds riskier than other related features, especially coupled with 20% page loads. So although the plan to monitor for 6 milestones sounds good, this approval does *not* extend to removal. Please come back to this thread closer to the proposed removal to see if the usage had dropped substantially.
On Sunday, November 9, 2025 at 7:47:04 PM UTC-5 Mike Taylor wrote: > Could you please request Debuggability and Testing bits in your > chromestatus entry > On 11/8/25 3:35 a.m., Nan Lin wrote: > > Intent to Deprecate and Remove: Attribution Reporting API > > Contact emails > > [email protected], [email protected], [email protected] > > Explainer > > https://github.com/WICG/attribution-reporting-api > > Specification > > https://wicg.github.io/attribution-reporting-api/ > > Summary > > The Attribution Reporting API (ARA) is a privacy-preserving web API > designed to measure ad conversions without third-party cookies or user > tracking across sites. > > Following Chrome's announcement > <https://privacysandbox.com/news/privacy-sandbox-next-steps/> that the > current approach to third-party cookies will be maintained, we are now > planning to deprecate and remove > <https://privacysandbox.com/news/update-on-plans-for-privacy-sandbox-technologies/> > > the Attribution Reporting API (along with certain other Privacy Sandbox > APIs, as outlined on the Privacy Sandbox feature status page > <https://privacysandbox.google.com/overview/status>). > > Blink component > > Internals > AttributionReporting > <https://bugs.chromium.org/p/chromium/issues/list?q=component:Internals%3EAttributionReporting> > > Web Feature ID > > None > > Motivation > > Chrome has announced > <https://privacysandbox.com/news/update-on-plans-for-privacy-sandbox-technologies/> > > that the current approach to third-party cookies will be maintained. Given > this, we expect adoption of the Attribution Reporting API to decrease over > time, as cross-site measurement will remain possible in Chrome using > third-party cookies. Further, although Microsoft Edge integrates with the > Attribution Reporting API, most other browser engines have not signaled > interest in launching the API. Removing this (and certain other Privacy > Sandbox APIs <https://privacysandbox.google.com/overview/status>) will > help focus efforts on the proposed interoperable Attribution > <https://github.com/w3c/attribution> standard. > > Developer-facing impact > > Sites that are using the Attribution Reporting API for conversion > measurement and do not migrate to alternative solutions may experience a > disruption in conversion measurement on eventual removal of the API code > from Chrome. > > > - > > Conversion measurement disruption: All ad conversion events relying on > the deprecated API will fail to register or report. Sites using this API > as > their primary or supplementary method for ad measurement will lose > visibility into campaign performance metrics derived from this technology. > - > > Public API surface: The following outlines the consequences of > deprecating and removing the Attribution Reporting API for each of the > interfaces defined here > <https://wicg.github.io/attribution-reporting-api/#idl-index>. > - > > Potentially user-breaking > - > > XMLHttpRequest.setAttributionReporting(): Calling > setAttributionReporting() on an XMLHttpRequest object will throw > an exception because the method will no longer exist. This is a > breaking > change for any site that calls this method. Given that this feature > is not > implemented in other browsers, it is likely that sites are already > using > feature detection to check the method’s existence before calling it, > which > would prevent breakage. We will start to track the usage of this > method. > - > > Non user-breaking > - > > HTMLAttributionSrcElementUtils and the attributionsrc attribute: > The attributionsrc attribute on <a>, <area>, <img>, and <script> > elements will be ignored. Any values assigned to this attribute will > have > no effect, and the browser will no longer initiate background > requests to > register attribution sources/triggers. Additionally we will no > longer > process trigger headers on legacy subresource requests that lack the > opt-in > (either on an element or fetch/XHR). This will not cause any visible > breakage or errors on the page for the user, but it will silently > prevent > conversion measurement for sites that rely on this attribute. > - > > attributionsrc in window.open(): The attributionsrc feature in > the features string of a window.open() call will be ignored. The > window will still open as requested, but no attribution source will > be > registered. This will not cause any visible breakage or errors on > the pages > for the user, but it will silently prevent conversion measurement > for sites > that rely on this functionality. > - > > AttributionReportingRequestOptions and the attributionReporting > member in RequestInit: The attributionReporting property within > the options of a fetch() call will be ignored. The fetch request > will still > be made, but it will not trigger any attribution-related > functionality. > This change will not cause any JavaScript errors, but conversion > measurement that relies on the fetch requests will no longer work. > - > > Attribution-Reporting-Eligible and Attribution-Reporting-Support > headers: Since the browser will no longer process the > attributionsrc attribute or the attributionReporting property in > requests, it will no longer send these two headers on outgoing > requests. > - > > attribution-reporting permission policy: The > attribution-reporting permission policy > > <https://wicg.github.io/attribution-reporting-api/#permission-policy-integration> > > will be removed along with the API. Since the API it controls will > no > longer exist, the permission policy will have no effect and its > removal is > not considered a breaking change. > > > > Planning and Estimated Milestones > > Deprecate the browser API surface in M144 and remove in M150. > > There will be one aspect of ARA that will end sooner. Server-side summary > report computation will no longer operate by late December 2025. We have > already communicated to the users of that service of these plans. Such > users can use debug reports instead until the removal of the ARA surface as > a whole. Since this impacts post-facto server-side operations, it will not > incur any user-facing breakage. > > Currently ~20% > <https://chromestatus.com/metrics/webfeature/timeline/popularity/282> of > page loads use the Attribution Reporting API. While ARA’s usage as a > percentage of page loads is quite high, it is driven by a small number of > third-party ad tech scripts present on a large number of sites. We will > continue to monitor usage in addition to providing comprehensive updates on > privacysandbox.google.com with the status of the API and deprecation plans > <https://privacysandbox.google.com/overview/status>. > > We will proactively work toward reducing ARA usage to low levels once this > intent is approved, including disallowing any new enrollment sign-ups, and > contacting enrolled sites to inform them about the deprecation timelines. > > Link to entry on the Chrome Platform Status > > https://chromestatus.com/feature/6320639375966208 > > -- > 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/beb44d6a-aae5-4664-994a-38fb93bb4580n%40chromium.org > > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/beb44d6a-aae5-4664-994a-38fb93bb4580n%40chromium.org?utm_medium=email&utm_source=footer> > . > > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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