v150 · 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

implementation reference

Need the exact API surface, compatibility boundaries, errors, lifecycle, and source links? Read the matching gendn reference ↗