Limited Availability Security

Connection allowlists

The Connection-Allowlist HTTP response header limits which requests a page may initiate using fetch and other APIs.

Baseline Status: This feature is currently Limited (not yet Baseline). Latest engine implementation shipped on Aug 28, 2026.

Desktop Browser Engine Support

Google Chrome

152

Supported

Mozilla Firefox

—

Unsupported

Apple Safari

—

Unsupported

Microsoft Edge

152

Supported

Mobile Browser Engine Support

Chrome Android

152

Firefox Android

—

Safari iOS

—

Specifications and References

MDN Browser Compat Data Keys: