v150 · removal · privacy sandbox

Deprecate and Remove: Related Website Sets (RWS)

Related Website Sets — the mechanism for declaring related-site relationships across origins, enabling limited cross-site cookie access via the Storage Access API — is being deprecated. With Chrome reversing its third-party cookie deprecation plan, RWS is no longer required and is being wound down.

concepts

  1. RWS Detection Probe

    Detects whether RWS-style features are present in your browser: the canonical-origin headers, the requestStorageAccessFor entry point, and the JSON descriptors. Useful for sites planning the migration off RWS.

  2. Storage Access Migration

    The recommended path off RWS, walked end to end: probe with hasStorageAccess(), request with requestStorageAccess(), write a cookie, and verify. Same API surface Safari and Firefox already ship.

  3. RWS Validator & Migration Guide

    Paste your .well-known/related-website-set.json manifest to validate its structure. Shows which fields Chrome 150 still reads (for now), which are deprecated, and the step-by-step Storage Access API migration path.

  4. RWS to CHIPS Migrator

    Paste a .well-known/related-website-sets.json manifest and get the equivalent CHIPS (Partitioned cookie attribute) configuration for every domain in the set. Includes a feature-detect panel and a privacy model comparison table.

  5. CHIPS Explainer

    Four-step guided explainer walking from what RWS allowed, why it was removed, the CHIPS partitioning concept (same embed on different top sites → different cookie jars), to the migration path. Includes an interactive Set-Cookie header builder that validates whether your cookie is a valid CHIPS cookie as you toggle each required attribute.

  6. Deprecation Timeline

    A scrollable timeline tracing the full arc of Related Website Sets — from the original Privacy Sandbox announcement (2019), through RWS shipping in Chrome 113, Google reversing third-party cookie deprecation (April 2024), to the Chrome 149 deprecation announcement and Chrome 150 wind-down. A companion table shows exactly which features still work in Chrome 150 vs what is gone, with the replacement for each.

    Timeline Privacy Sandbox Migration guide

why it shipped

RWS was a key load-bearing piece of the original Privacy Sandbox plan: in a world without third-party cookies, sites within the same business needed some way to express a "first-party-ish" relationship across origins. After Chrome decided to keep third-party cookies, the cost-benefit of maintaining RWS no longer made sense. The deprecation is being announced now so sites that adopted RWS have time to migrate before the API actually disappears in a future Chrome.

references

implementation reference

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