Cross-Origin Resource Sharing (CORS)

Mechanism where servers opt in to cross-origin requests via HTTP headers, enforcing origin-based access controls.

#web#security#headers

Last updated: 2025-09-07T00:00:00.000Z

Differences across sources

Parallel sources use distinct terminology or emphasize different aspects. Review each citation to understand scope and normative intent.

Evidence

OTHER WHATWG Fetch Standard — CORS Normative evidence
OTHER W3C CORS (historical) Informative evidence
www.w3.org

More context

CORS augments the SOP by defining preflight and response headers that explicitly permit cross‑origin requests.