v152 · removal · privacy sandbox

Deprecate and remove: Attribution Reporting API

The Attribution Reporting API — Chrome's privacy-preserving alternative to cross-site cookies for ad conversion measurement — is being deprecated. The reversal on third-party cookie deprecation makes the API's stack of trade-offs no longer warranted.

concepts

  1. Surface Inventory

    Lists every Attribution Reporting API surface present in your browser: the registration headers, the source / trigger registration objects, the debug reports endpoint, and the relevant flags. Watch them disappear release by release.

  2. Header Probe

    Pokes the network-level entry points — attributionsrc attributes on anchors and images, the fetch() attributionReporting option, and the relevant Permissions Policy. Shows live / gone state for each surface as the deprecation rolls forward.

  3. Removal Timeline

    A release-by-release timeline of the ARA deprecation from Chrome 117 through Chrome 151+, with a live probe of every remaining API surface in this browser and a migration table mapping each deprecated surface to its first-party server-side replacement.

  4. Attribution Migration Guide

    A four-step migration wizard covering every ARA surface with its first-party replacement: attributionsrc → server-side pixel, aggregate reports → measurement endpoint, debug reports → server logs. Each step includes before/after code snippets, a live feature-detection probe showing ARA surface availability in this browser, and a checklist to track your migration progress.

  5. Event Source Comparison

    Side-by-side comparison of the old Attribution Reporting API event-level source registration flow (5-step attributionsrc → browser storage chain) against the recommended server-side replacement. Includes a live API surface probe that detects attributionsrc attribute availability and featurePolicy status in the current browser.

  6. Privacy Migration Planner

    Select the Attribution Reporting surfaces still in use and generate a first-party measurement replacement plan, including server-side conversion handling, privacy thresholds, debug logging, and iframe policy cleanup.

why it shipped

The Attribution Reporting API was designed for a future without third-party cookies. It traded fine-grained click-stream tracking for noisy, aggregated reports — a deliberately privacy-preserving design that came at significant complexity cost for advertisers and a real engineering burden for Chrome to maintain. With third-party cookies sticking around, advertisers have no need to migrate, and Chrome has no reason to keep the API. The deprecation is staged: feature detection still works, then APIs start returning errors, then they disappear entirely.

references