Cross-origin isolation

Cross-origin isolation enables a web page to use powerful features such as SharedArrayBuffer. An extension can opt into cross-origin isolation by specifying the appropriate values for the cross_origin_embedder_policy and cross_origin_opener_policy manifest keys. For example, a manifest like the one below will opt the extension's origin into cross-origin isolation.

  "name": "CrossOriginIsolation example",
  "manifest_version": 3,
  "version": "1.1",
  "cross_origin_embedder_policy": {
    "value": "require-corp"
  "cross_origin_opener_policy": {
    "value": "same-origin"

Opting into cross-origin isolation allows the extension to use powerful APIs like SharedArrayBuffers in its cross-origin isolated contexts. However, it does also come with certain side-effects. See Making your website "cross-origin isolated" using COOP and COEP for more information on this.