v150 · Privacy · Migration

Attribution Migration Guide

The Attribution Reporting API (ARA) is being removed in Chrome 150. This interactive wizard walks you through detecting your ARA usage, mapping to Privacy Sandbox alternatives, and verifying the migration.

1 Detect

2 Map

3 Code

4 Timeline

5 Checklist

Step 1: Which ARA features are you using?

Select the ARA features present in your codebase to get a tailored migration plan.

Feature probe — live browser check

Step 2: ARA → Privacy Sandbox alternatives

ARA feature (removed)	Recommended alternative	Notes
Event-level reports	Protected Audience API — reporting worklets	Click/view attribution via PA auction reporting
Aggregatable reports	Private Aggregation API	Noisy aggregates from within PA or Shared Storage
Attribution-Reporting-Register-Source header	Topics API + server-side aggregation	Interest-based signals without cross-site identity
Attribution-Reporting-Register-Trigger header	Protected Audience conversion reporting	Trigger from within fenced frames
Aggregation coordinator	Private Aggregation API with TEE coordinator	Same coordinator infrastructure, different entry point
attributionsrc attribute	Fenced Frame + reportEvent()	Signal events from isolated ad frames

Step 3: Code comparison

Old ARA header-based approach vs. new Privacy Sandbox alternative.

Old — ARA header (removed Chrome 150)
// Server sets on source registration:
Attribution-Reporting-Register-Source: {
  "destination": "https://advertiser.example",
  "source_event_id": "412444888111012",
  "expiry": 604800,
  "priority": 100,
  "aggregation_keys": {
    "campaignCounts": "0x159"
  }
}

// Trigger registration:
Attribution-Reporting-Register-Trigger: {
  "event_trigger_data": [{"trigger_data": "1"}],
  "aggregatable_trigger_data": [...],
  "aggregatable_values": {...}
}

New — Private Aggregation API
// In a Shared Storage worklet:
class MeasurementOperation {
  async run(data) {
    // Encode conversion signal
    const bucket = BigInt(data.campaignId);
    const value  = data.converted ? 1 : 0;

    // Report via TEE-based aggregation
    // (no cross-site identity leaked)
    privateAggregation
      .contributeToHistogram({
        bucket,
        value
      });
  }
}
register('measure-conversion',
  MeasurementOperation);

Step 4: Chrome 150 removal timeline

Chrome 104–148

ARA in origin trial / available

ARA headers and JS APIs available behind origin trial flag

Chrome 149

Deprecation intent announced

Console deprecation warnings added; blink-dev intent to remove published

Chrome 150 (current)

ARA removed from stable

attributionsrc, Attribution-Reporting-* headers, and JS registration APIs removed

Post-Chrome 150

Private Aggregation API stable

Full replacement surface available; Privacy Sandbox APIs stable for production use

Step 5: Migration checklist

Click each item to toggle pass/fail. Green = done, red = still outstanding.

implementation reference

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